The Securities and Exchange Commission has not necessarily reviewed the information in this filing and has not determined if it is accurate and complete.
The reader should not assume that the information is accurate and complete.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 13F

FORM 13F INFORMATION TABLE
OMB APPROVAL
OMB Number: 3235-0006
Estimated average burden
hours per response: 23.8
COLUMN 1 COLUMN 2 COLUMN 3 COLUMN 4 COLUMN 5 COLUMN 6 COLUMN 7 COLUMN 8
VALUE SHRS OR SH/ PUT/ INVESTMENT OTHER VOTING AUTHORITY
NAME OF ISSUER TITLE OF CLASS CUSIP (x$1000) PRN AMT PRN CALL DISCRETION MANAGER SOLE SHARED NONE
3-D SYS CORP DEL COM NEW COM 88554D205 768 41,048 SH   SOLE   41,048 0 0
3M COMPANY COM 88579y101 1,391 6,680 SH   SOLE   6,680 0 0
AAC HOLDINGS INC COM 000307108 7,281 1,050,597 SH   SOLE   1,050,597 0 0
ABBOTT LABORATORIES COM 002824100 549 11,288 SH   SOLE   11,288 0 0
ABBVIE INC SHS COM 00287y109 567 7,821 SH   SOLE   7,821 0 0
AIR PRODUCTS & CHEMICALS, INC. COM 009158106 260 1,820 SH   SOLE   1,820 0 0
ALPHABET INC CLASS C COM 02079K107 86,503 95,191 SH   SOLE   95,191 0 0
ALPHABET INC. CLASS A COM 02079k305 784 843 SH   SOLE   843 0 0
AMAZON.COM INC COM 023135106 57,579 59,482 SH   SOLE   59,482 0 0
AMERICAN TOWER REIT INC COM 03027X100 89,496 676,358 SH   SOLE   676,358 0 0
AMGEN INC COM PV $0.0001 COM 031162100 261 1,515 SH   SOLE   1,515 0 0
ANSYS INC COM 03662Q105 153,752 1,263,573 SH   SOLE   1,263,573 0 0
APPLE INC COM 037833100 1,171 8,134 SH   SOLE   8,134 0 0
ATRION CORPORATION COM 049904105 6,205 9,646 SH   SOLE   9,646 0 0
AUTOMATIC DATA PROC COM 053015103 2,265 22,106 SH   SOLE   22,106 0 0
BEACON ROOFING SUPPLY INC COM 073685109 744 15,190 SH   SOLE   15,190 0 0
BECTON DICKINSON&CO COM 075887109 301 1,541 SH   SOLE   1,541 0 0
BERKLEY W R CORP COM 084423102 3,272 47,308 SH   SOLE   47,308 0 0
BERKSHIRE HATHAWAY INC DELAWA COM 084670108 1,528 6 SH   SOLE   6 0 0
BERKSHIRE HATHAWAYINC DEL CL COM 084670702 3,656 21,587 SH   SOLE   21,587 0 0
BIO-TECHNE CORP COM 09073M104 46,566 396,308 SH   SOLE   396,308 0 0
BLACKBAUD INC COM 09227Q100 61,885 721,689 SH   SOLE   721,689 0 0
BLACKLINE COM 09239b109 66,879 1,871,273 SH   SOLE   1,871,273 0 0
BRIGHT HORIZONS FAM SOL IN DEL COM 109194100 319 4,127 SH   SOLE   4,127 0 0
CALAVO GROWERS INC COM 128246105 412 5,967 SH   SOLE   5,967 0 0
CAMPBELL SOUP CO COM COM 134429109 209 4,000 SH   SOLE   4,000 0 0
CANADIAN NATL RY CO COM COM 136375102 1,621 20,000 SH   SOLE   20,000 0 0
CAPITAL ONE FINL CORP COM COM 14040H105 2,000 24,204 SH   SOLE   24,204 0 0
CARMAX INC COM 143130102 98,753 1,566,014 SH   SOLE   1,566,014 0 0
CARTER'S INC COM 146229109 270 3,032 SH   SOLE   3,032 0 0
CBRE GROUP INC COM 12504L109 38,824 1,066,602 SH   SOLE   1,066,602 0 0
CELGENE CORP COM 151020104 114,856 884,391 SH   SOLE   884,391 0 0
CHEVRON CORP COM 166764100 669 6,417 SH   SOLE   6,417 0 0
CHIPOTLE MEXICAN GRILL CL A COM 169656105 220 529 SH   SOLE   529 0 0
CISCO SYSTEMS INC COM COM 17275r102 2,096 66,971 SH   SOLE   66,971 0 0
COCA COLA COM COM 191216100 1,703 37,963 SH   SOLE   37,963 0 0
COGENT COMMUNICATIONS COM 19239V302 1,103 27,518 SH   SOLE   27,518 0 0
COGNIZANT TECHNOLOGY SOLUTIONS COM 192446102 266 4,000 SH   SOLE   4,000 0 0
COLFAX CORPORATION COM 194014106 457 11,606 SH   SOLE   11,606 0 0
COLGATE-PALMOLIVE CO COM 194162103 736 9,925 SH   SOLE   9,925 0 0
COMCAST CORP NEW CL A COM 20030n101 4,141 106,406 SH   SOLE   106,406 0 0
COMPUTER MODELLING LTD COM 205249105 299 38,482 SH   SOLE   38,482 0 0
CORELOGIC INC COM 21871D103 827 19,072 SH   SOLE   19,072 0 0
COSTAR GROUP INC COM 22160N109 97,032 368,103 SH   SOLE   368,103 0 0
CROWN CASTLE REIT INC SHS COM 22822v101 6,662 66,500 SH   SOLE   66,500 0 0
DEXCOM INC COM 252131107 1,031 14,094 SH   SOLE   14,094 0 0
DISCOVER FINANCIAL SERVICES (U COM 254709108 49,759 800,106 SH   SOLE   800,106 0 0
DISNEY (WALT) CO COM STK COM 254687106 1,150 10,826 SH   SOLE   10,826 0 0
DOLLAR GENERAL COM 256677105 207 2,874 SH   SOLE   2,874 0 0
DOUGLAS DYNAMICS INC COM 25960R105 1,855 56,392 SH   SOLE   56,392 0 0
DU PONT EI DE NEMOUR COM 263534109 284 3,518 SH   SOLE   3,518 0 0
DUKE REALTY CORP REIT COM 264411505 334 11,950 SH   SOLE   11,950 0 0
DULUTH HOLDINGS INC COM 26443V101 883 48,470 SH   SOLE   48,470 0 0
EAST WEST BANCORP INC COM 27579r104 439 7,500 SH   SOLE   7,500 0 0
ECOLAB INC COM 278865100 148,962 1,122,122 SH   SOLE   1,122,122 0 0
EDWARDS LIFESCIENCES COM 28176e108 1,479 12,506 SH   SOLE   12,506 0 0
ELI LILLY & CO COM 532457108 687 8,353 SH   SOLE   8,353 0 0
ELLIE MAE INC COM 28849P100 4,964 45,167 SH   SOLE   45,167 0 0
EMERSON ELECTRIC CO COM 291011104 737 12,357 SH   SOLE   12,357 0 0
ENTERPRISE PRDTS PRTN LPL P COM 293792107 465 17,175 SH   SOLE   17,175 0 0
ENVESTNET INC COM 29404K106 58,377 1,474,175 SH   SOLE   1,474,175 0 0
EQUITY RESIDENTIAL REIT COM 29476l107 370 5,626 SH   SOLE   5,626 0 0
EVERTEC INC COM 30040P103 344 19,866 SH   SOLE   19,866 0 0
EXPONENT INC COM 30214U102 27,992 480,141 SH   SOLE   480,141 0 0
EXPRESS SCRIPTS HLDG COM 30219g108 1,018 15,941 SH   SOLE   15,941 0 0
EXXON MOBIL CORP COM COM 30231g102 1,596 19,775 SH   SOLE   19,775 0 0
FASTENAL CO COM 311900104 63,091 1,449,371 SH   SOLE   1,449,371 0 0
FISERV INC COM 337738108 8,387 68,553 SH   SOLE   68,553 0 0
FORTINET INC COM COM 34959E109 384 10,263 SH   SOLE   10,263 0 0
GENERAL ELECTRIC COM 369604103 3,342 123,742 SH   SOLE   123,742 0 0
GENESEE AND WYO INC CL A COM 371559105 498 7,278 SH   SOLE   7,278 0 0
GENUINE PARTS CO COM 372460105 462 4,984 SH   SOLE   4,984 0 0
GLACIER BANCORP INC NEW COM 37637Q105 314 8,571 SH   SOLE   8,571 0 0
GOOD TIMES RESTAURANTS INC COM 382140879 114 32,062 SH   SOLE   32,062 0 0
GUIDEWIRE SOFTWARE INC COM 40171V100 946 13,775 SH   SOLE   13,775 0 0
HCP INC COM 40414l109 1,933 60,471 SH   SOLE   60,471 0 0
HEALTHCARE SERVICES GROUP INC COM 421906108 71,147 1,519,260 SH   SOLE   1,519,260 0 0
HEALTHSTREAM INC COM 42222N103 423 16,070 SH   SOLE   16,070 0 0
HEICO CORP NEW CL A COM 422806208 842 13,567 SH   SOLE   13,567 0 0
HOME DEPOT INC COM 437076102 399 2,600 SH   SOLE   2,600 0 0
HONEYWELL INTL INC COM 438516106 203 1,520 SH   SOLE   1,520 0 0
IBM CORP COM 459200101 1,111 7,220 SH   SOLE   7,220 0 0
IDEXX LABORATORIES INC COM 45168D104 19,790 122,599 SH   SOLE   122,599 0 0
ILLINOIS TOOL WORKS COM 452308109 294 2,050 SH   SOLE   2,050 0 0
ILLUMINA INC COM 452327109 81,171 467,789 SH   SOLE   467,789 0 0
IMAX CORP COM 45245E109 24,811 1,127,759 SH   SOLE   1,127,759 0 0
INTEL CORP COM 458140100 11,201 331,982 SH   SOLE   331,982 0 0
INTUITIVE SURGICAL INC COM 46120E602 134,019 143,279 SH   SOLE   143,279 0 0
JOHN BEAN TECHNOLOGIES COM 477839104 451 4,600 SH   SOLE   4,600 0 0
JOHNSON AND JOHNSON COM COM 478160104 11,420 86,325 SH   SOLE   86,325 0 0
JPMORGAN CHASE & CO COM 46625h100 391 4,280 SH   SOLE   4,280 0 0
KEYON COMMUNI HOLD INC COM 493312201 0 16,667 SH   SOLE   16,667 0 0
KIMBERLY CLARK COM 494368103 305 2,363 SH   SOLE   2,363 0 0
LABORATORY CORP AMER HLDGS COM COM 50540R409 2,777 18,013 SH   SOLE   18,013 0 0
LCI INDUSTRIES COM 50189k103 499 4,870 SH   SOLE   4,870 0 0
LIBERTY TRIPADVISOR HLDGS INC COM 531465102 183 15,799 SH   SOLE   15,799 0 0
LINCOLN NTL CORP IND NPV COM 534187109 754 11,155 SH   SOLE   11,155 0 0
LITHIA MOTORS INC CL A COM 536797103 664 7,051 SH   SOLE   7,051 0 0
LITTELFUSE INC COM 537008104 211 1,278 SH   SOLE   1,278 0 0
LKQ CORP COM 501889208 110,056 3,340,088 SH   SOLE   3,340,088 0 0
M & T BANK CORP COM 55261f104 663 4,095 SH   SOLE   4,095 0 0
MAGELLAN MIDSTREAM PRTNRS LP C COM 559080106 257 3,600 SH   SOLE   3,600 0 0
MARKEL CORP HLDG CO COM 570535104 92,000 94,276 SH   SOLE   94,276 0 0
MASTERCARD INC-CLASS A COM 57636Q104 60,283 496,358 SH   SOLE   496,358 0 0
MCCORMICK & CO INC COM NON VTG COM 579780206 1,281 13,139 SH   SOLE   13,139 0 0
MERCK AND CO INC SHS COM 58933y105 1,534 23,928 SH   SOLE   23,928 0 0
MESA LABS INC COM 59064R109 1,217 8,494 SH   SOLE   8,494 0 0
MICROSOFT CORP COM 594918104 3,699 53,658 SH   SOLE   53,658 0 0
MIDDLEBY CORP COM 596278101 2,100 17,285 SH   SOLE   17,285 0 0
MONRO MUFFLER BRAKE INC COM 610236101 913 21,874 SH   SOLE   21,874 0 0
MOODYS CORP COM 615369105 122,489 1,006,651 SH   SOLE   1,006,651 0 0
MSC INDUSTRIAL DIRECT CO INC C COM 553530106 275 3,204 SH   SOLE   3,204 0 0
NASPERS SPON ADR EACH REP 0.2 COM 631512209 482 24,800 SH   SOLE   24,800 0 0
NATIONAL AMERICAN UNIVER COM 63245q105 37 15,000 SH   SOLE   15,000 0 0
NATIONAL HEALTHCARE CORP COM 635906100 284 4,051 SH   SOLE   4,051 0 0
NAVIGATORS GROUP INC COM 638904102 253 4,601 SH   SOLE   4,601 0 0
NEOGEN CORP COM COM 640491106 677 9,800 SH   SOLE   9,800 0 0
NESTLE S A REP RG SH ADR COM 641069406 518 5,942 SH   SOLE   5,942 0 0
NORFOLK SOUTHERN CO COM 655844108 280 2,299 SH   SOLE   2,299 0 0
O REILLY AUTOMOTIVE INC COM 67103H107 13,243 60,544 SH   SOLE   60,544 0 0
ONEBEACON INSURANCE GROUP LTD COM G67742109 670 36,735 SH   SOLE   36,735 0 0
PAYCHEX INC COM 704326107 3,218 56,521 SH   SOLE   56,521 0 0
PEPSICO INC COM 713448108 660 5,713 SH   SOLE   5,713 0 0
PFIZER INC COM 717081103 1,040 30,968 SH   SOLE   30,968 0 0
PHILIP MORRIS INTL COM 718172109 410 3,493 SH   SOLE   3,493 0 0
PINNACLE WEST CAP CORP COM 723484101 255 3,000 SH   SOLE   3,000 0 0
PIONEER NAT RES CO COM COM 723787107 231 1,450 SH   SOLE   1,450 0 0
PNC FINCL SERVICES GROUP COM 693475105 2,239 17,934 SH   SOLE   17,934 0 0
POOL CORPORATION COM 73278l105 375 3,188 SH   SOLE   3,188 0 0
POTASH CORP SASKATCHEWAN COM 73755l107 500 30,650 SH   SOLE   30,650 0 0
PRA GROUP INC COM 69354N106 334 8,823 SH   SOLE   8,823 0 0
PRICE T ROWE GROUP INC COM 74144T108 11,259 151,720 SH   SOLE   151,720 0 0
PROASSURANCE CORP COM 74267C106 248 4,086 SH   SOLE   4,086 0 0
PROCTER & GAMBLE CO COM 742718109 18,280 209,759 SH   SOLE   209,759 0 0
PROS HOLDINGS INC COM 74346Y103 63,476 2,317,471 SH   SOLE   2,317,471 0 0
QUALCOMM INC COM 747525103 21,261 385,029 SH   SOLE   385,029 0 0
RED HAT INC COM 756577102 156,379 1,633,197 SH   SOLE   1,633,197 0 0
REXNORD CORP COM 76169B102 411 17,683 SH   SOLE   17,683 0 0
ROPER TECHNOLOGIES INC COM 776696106 168,202 726,482 SH   SOLE   726,482 0 0
RPM INTERNATIONAL INC COM 749685103 239 4,385 SH   SOLE   4,385 0 0
S & P GLOBAL INC COM 78409V104 81,864 560,748 SH   SOLE   560,748 0 0
SBA COMMUNICATIONS CORP CL A COM 78410G104 24,805 183,879 SH   SOLE   183,879 0 0
SCHLUMBERGER LTD COM 806857108 6,826 103,669 SH   SOLE   103,669 0 0
SEI INVESTMENTS CO COM 784117103 126,633 2,354,653 SH   SOLE   2,354,653 0 0
SIGNET JEWELERS LTD COM G81276100 672 10,632 SH   SOLE   10,632 0 0
SITEONE COM 82982l103 257 4,937 SH   SOLE   4,937 0 0
SMITH & NEPHEW P L C ADS COM 83175M205 376 10,800 SH   SOLE   10,800 0 0
SOTHERLY HOTELS INC COM COM 83600C103 79 11,625 SH   SOLE   11,625 0 0
SPS COMMERCE INC COM 78463M107 404 6,339 SH   SOLE   6,339 0 0
STERIS PLC COM G84720104 74,146 909,766 SH   SOLE   909,766 0 0
TELADOC INC COM 87918A105 1,749 50,394 SH   SOLE   50,394 0 0
TESLA INC COM 88160R101 244 676 SH   SOLE   676 0 0
TRANSDIGM GROUP INC COM 893641100 66,339 246,733 SH   SOLE   246,733 0 0
TRIMBLE INC COM 896239100 89,133 2,498,834 SH   SOLE   2,498,834 0 0
TYLER TECHNOLOGIES INC COM 902252105 105,774 602,119 SH   SOLE   602,119 0 0
U S BANCORP COM 902973304 1,645 31,686 SH   SOLE   31,686 0 0
ULTIMATE SOFTWARE GROUP INC COM 90385D107 521 2,482 SH   SOLE   2,482 0 0
UNITED PARCEL SERVICE INC CL B COM 911312106 342 3,097 SH   SOLE   3,097 0 0
UNITED TECHS CORP COM COM 913017109 497 4,070 SH   SOLE   4,070 0 0
VENTAS INC REIT COM 92276f100 2,059 29,632 SH   SOLE   29,632 0 0
VERISK ANALYTICS INC COM 92345Y106 122,980 1,457,631 SH   SOLE   1,457,631 0 0
VERIZON COMMUNICATNS COM COM 92343v104 380 8,506 SH   SOLE   8,506 0 0
VISA INC CL A COM 92826C839 134,503 1,434,244 SH   SOLE   1,434,244 0 0
W.P. CAREY INC. REIT COM 92936u109 381 5,779 SH   SOLE   5,779 0 0
WABTEC COM 929740108 101,340 1,107,540 SH   SOLE   1,107,540 0 0
WAGEWORKS INC COM 930427109 102,516 1,525,539 SH   SOLE   1,525,539 0 0
WASTE CONNECTIONS INC COM 94106B101 94,677 1,469,678 SH   SOLE   1,469,678 0 0
WATSCO INC COM COM 942622200 52,745 342,053 SH   SOLE   342,053 0 0
WAYFAIR COM 94419l101 542 7,048 SH   SOLE   7,048 0 0
WELLS FARGO & CO COM 949746101 424 7,659 SH   SOLE   7,659 0 0
WELLTOWER INC COM 95040q104 393 5,246 SH   SOLE   5,246 0 0
WHOLE FOODS MKT INC COM COM 966837106 488 11,590 SH   SOLE   11,590 0 0
WSFS FINANCIAL CORP COM 929328102 1,697 37,423 SH   SOLE   37,423 0 0
ZOE'S KITCHEN INC COM 98979J109 166 13,978 SH   SOLE   13,978 0 0
ZURICH INSURANCE GROUP-ADR COM 989825104 221 7,600 SH   SOLE   7,600 0 0
BLACKROCK ENHANCED EQT DIV TR ETFS 09251A104 88 10,000 SH   SOLE   10,000 0 0
DEUTSCHE X-TRACKERS MSCI EUROP ETFS 233051853 238 8,699 SH   SOLE   8,699 0 0
ISHARES CORE S&P MID CAP ETF ETFS 464287507 1,015 5,834 SH   SOLE   5,834 0 0
ISHARES CORE S&P SMALL CAP ETF ETFS 464287804 645 9,199 SH   SOLE   9,199 0 0
ISHARES MSCI EAFE ETF ETFS 464287465 267 4,099 SH   SOLE   4,099 0 0
VANGUARD DIVIDEND APPREC ETFS 921908844 1,105 11,925 SH   SOLE   11,925 0 0
VANGUARD FTSE ALL WORLD EX US ETFS 922042775 3,329 66,541 SH   SOLE   66,541 0 0
VANGUARD FTSE EMERGING MARK ET ETFS 922042858 847 20,738 SH   SOLE   20,738 0 0
VANGUARD HIGH DVD YIELD ETF ETFS 921946406 796 10,186 SH   SOLE   10,186 0 0
VANGUARD INDEX FDS FORMERLY VA ETFS 922908363 5,105 22,989 SH   SOLE   22,989 0 0
VANGUARD REIT ETF ETFS 922908553 750 9,015 SH   SOLE   9,015 0 0
VANGUARD SHORT-TERM GOV BD ETFS 92206c102 439 7,225 SH   SOLE   7,225 0 0
VANGUARD TOTAL STK MKT ETF ETFS 922908769 325 2,615 SH   SOLE   2,615 0 0
WISDOMTREE TR INDIA ERNGS FD ETFS 97717W422 306 12,500 SH   SOLE   12,500 0 0