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 747 49,935 SH   SOLE   49,935 0 0
3M COMPANY COM 88579y101 768 4,014 SH   SOLE   4,014 0 0
AAC HOLDINGS INC COM 000307108 8,961 1,050,507 SH   SOLE   1,050,507 0 0
ABBOTT LABORATORIES COM 002824100 501 11,288 SH   SOLE   11,288 0 0
ABBVIE INC SHS COM 00287y109 510 7,821 SH   SOLE   7,821 0 0
ALPHABET INC CLASS C COM 02079K107 80,305 96,804 SH   SOLE   96,804 0 0
ALPHABET INC. CLASS A COM 02079k305 715 843 SH   SOLE   843 0 0
AMAZON.COM INC COM 023135106 53,637 60,502 SH   SOLE   60,502 0 0
AMERICAN TOWER REIT INC COM 03027X100 83,541 687,352 SH   SOLE   687,352 0 0
AMGEN INC COM PV $0.0001 COM 031162100 249 1,515 SH   SOLE   1,515 0 0
ANSYS INC COM 03662Q105 140,438 1,314,099 SH   SOLE   1,314,099 0 0
APPLE INC COM 037833100 853 5,941 SH   SOLE   5,941 0 0
APPLIED MINERALS INC COM 03823m100 6 80,000 SH   SOLE   80,000 0 0
ATRION CORPORATION COM 049904105 4,683 10,003 SH   SOLE   10,003 0 0
AUTOMATIC DATA PROC COM 053015103 2,263 22,106 SH   SOLE   22,106 0 0
BEACON ROOFING SUPPLY INC COM 073685109 224 4,555 SH   SOLE   4,555 0 0
BECTON DICKINSON&CO COM 075887109 319 1,741 SH   SOLE   1,741 0 0
BERKLEY W R CORP COM 084423102 3,359 47,558 SH   SOLE   47,558 0 0
BERKSHIRE HATHAWAY INC DELAWA COM 084670108 1,499 6 SH   SOLE   6 0 0
BERKSHIRE HATHAWAYINC DEL CL COM 084670702 3,446 20,672 SH   SOLE   20,672 0 0
BIO-TECHNE CORP COM 09073M104 41,392 407,197 SH   SOLE   407,197 0 0
BLACKBAUD INC COM 09227Q100 66,915 872,770 SH   SOLE   872,770 0 0
BLACKLINE COM 09239b109 15,442 518,893 SH   SOLE   518,893 0 0
CALAVO GROWERS INC COM 128246105 348 5,743 SH   SOLE   5,743 0 0
CAMPBELL SOUP CO COM COM 134429109 229 4,000 SH   SOLE   4,000 0 0
CANADIAN NATL RY CO COM COM 136375102 1,479 20,000 SH   SOLE   20,000 0 0
CAPITAL ONE FINL CORP COM COM 14040H105 2,098 24,204 SH   SOLE   24,204 0 0
CARMAX INC COM 143130102 86,907 1,467,534 SH   SOLE   1,467,534 0 0
CBRE GROUP INC COM 12504L109 29,622 851,448 SH   SOLE   851,448 0 0
CELGENE CORP COM 151020104 111,262 894,174 SH   SOLE   894,174 0 0
CHEVRON CORP COM 166764100 689 6,417 SH   SOLE   6,417 0 0
CHIPOTLE MEXICAN GRILL CL A COM 169656105 272 611 SH   SOLE   611 0 0
CISCO SYSTEMS INC COM COM 17275r102 2,286 67,646 SH   SOLE   67,646 0 0
COCA COLA COM COM 191216100 1,057 24,914 SH   SOLE   24,914 0 0
COGENT COMMUNICATIONS COM 19239V302 671 15,598 SH   SOLE   15,598 0 0
COGNIZANT TECHNOLOGY SOLUTIONS COM 192446102 238 4,000 SH   SOLE   4,000 0 0
COLGATE-PALMOLIVE CO COM 194162103 726 9,925 SH   SOLE   9,925 0 0
COMCAST CORP NEW CL A COM 20030n101 4,000 106,406 SH   SOLE   106,406 0 0
COMPUTER MODELLING LTD COM 205249105 255 33,490 SH   SOLE   33,490 0 0
CORELOGIC INC COM 21871D103 559 13,720 SH   SOLE   13,720 0 0
COSTAR GROUP INC COM 22160N109 86,230 416,127 SH   SOLE   416,127 0 0
CROWN CASTLE REIT INC SHS COM 22822v101 6,411 67,879 SH   SOLE   67,879 0 0
DEXCOM INC COM 252131107 817 9,639 SH   SOLE   9,639 0 0
DISCOVER FINANCIAL SERVICES (U COM 254709108 45,099 659,438 SH   SOLE   659,438 0 0
DISNEY (WALT) CO COM STK COM 254687106 1,019 8,987 SH   SOLE   8,987 0 0
DOUGLAS DYNAMICS INC COM 25960R105 1,704 55,604 SH   SOLE   55,604 0 0
DU PONT EI DE NEMOUR COM 263534109 283 3,518 SH   SOLE   3,518 0 0
DUKE REALTY CORP REIT COM 264411505 324 12,350 SH   SOLE   12,350 0 0
DULUTH HOLDINGS INC COM 26443V101 1,279 60,066 SH   SOLE   60,066 0 0
EAST WEST BANCORP INC COM 27579r104 387 7,500 SH   SOLE   7,500 0 0
ECOLAB INC COM 278865100 143,550 1,145,281 SH   SOLE   1,145,281 0 0
EDWARDS LIFESCIENCES COM 28176e108 694 7,381 SH   SOLE   7,381 0 0
ELI LILLY & CO COM 532457108 703 8,353 SH   SOLE   8,353 0 0
ELLIE MAE INC COM 28849P100 4,641 46,281 SH   SOLE   46,281 0 0
EMERSON ELECTRIC CO COM 291011104 616 10,287 SH   SOLE   10,287 0 0
ENTERPRISE PRDTS PRTN LPL P COM 293792107 474 17,175 SH   SOLE   17,175 0 0
ENVESTNET INC COM 29404K106 48,736 1,508,842 SH   SOLE   1,508,842 0 0
EQUITY RESIDENTIAL REIT COM 29476l107 350 5,626 SH   SOLE   5,626 0 0
EVERTEC INC COM 30040P103 172 10,832 SH   SOLE   10,832 0 0
EXPONENT INC COM 30214U102 29,435 494,285 SH   SOLE   494,285 0 0
EXPRESS SCRIPTS HLDG COM 30219g108 1,051 15,941 SH   SOLE   15,941 0 0
EXXON MOBIL CORP COM COM 30231g102 1,679 20,474 SH   SOLE   20,474 0 0
FASTENAL CO COM 311900104 66,339 1,288,138 SH   SOLE   1,288,138 0 0
FISERV INC COM 337738108 7,907 68,568 SH   SOLE   68,568 0 0
FORTINET INC COM COM 34959E109 647 16,863 SH   SOLE   16,863 0 0
GENERAL ELECTRIC COM 369604103 3,480 116,769 SH   SOLE   116,769 0 0
GENUINE PARTS CO COM 372460105 461 4,984 SH   SOLE   4,984 0 0
GOOD TIMES RESTAURANTS INC COM 382140879 101 32,056 SH   SOLE   32,056 0 0
GUIDEWIRE SOFTWARE INC COM 40171V100 520 9,225 SH   SOLE   9,225 0 0
HCP INC COM 40414l109 1,893 60,503 SH   SOLE   60,503 0 0
HEALTHCARE SERVICES GROUP INC COM 421906108 67,030 1,555,585 SH   SOLE   1,555,585 0 0
HEICO CORP NEW CL A COM 422806208 475 6,339 SH   SOLE   6,339 0 0
HOME DEPOT INC COM 437076102 383 2,608 SH   SOLE   2,608 0 0
IBM CORP COM 459200101 1,231 7,070 SH   SOLE   7,070 0 0
IDEXX LABORATORIES INC COM 45168D104 19,011 122,964 SH   SOLE   122,964 0 0
ILLINOIS TOOL WORKS COM 452308109 272 2,050 SH   SOLE   2,050 0 0
ILLUMINA INC COM 452327109 72,526 425,021 SH   SOLE   425,021 0 0
IMAX CORP COM 45245E109 96,213 2,829,790 SH   SOLE   2,829,790 0 0
INTEL CORP COM 458140100 12,141 336,591 SH   SOLE   336,591 0 0
INTUITIVE SURGICAL INC COM 46120E602 117,558 153,376 SH   SOLE   153,376 0 0
INVENTURE FOODS INC COM 461212102 76 17,242 SH   SOLE   17,242 0 0
JOHN BEAN TECHNOLOGIES COM 477839104 237 2,700 SH   SOLE   2,700 0 0
JOHNSON AND JOHNSON COM COM 478160104 10,816 86,844 SH   SOLE   86,844 0 0
JPMORGAN CHASE & CO COM 46625h100 433 4,929 SH   SOLE   4,929 0 0
KEYON COMMUNI HOLD INC COM 493312201 0 16,667 SH   SOLE   16,667 0 0
KIMBERLY CLARK COM 494368103 312 2,373 SH   SOLE   2,373 0 0
LABORATORY CORP AMER HLDGS COM COM 50540R409 2,613 18,213 SH   SOLE   18,213 0 0
LIBERTY TRIPADVISOR HLDGS INC COM 531465102 167 11,840 SH   SOLE   11,840 0 0
LINCOLN NTL CORP IND NPV COM 534187109 328 5,017 SH   SOLE   5,017 0 0
LITHIA MOTORS INC CL A COM 536797103 350 4,091 SH   SOLE   4,091 0 0
LKQ CORP COM 501889208 110,105 3,761,714 SH   SOLE   3,761,714 0 0
LOWE'S COMPANIES INC COM 548661107 205 2,489 SH   SOLE   2,489 0 0
LYNAS CORP LTD AUD PA COM q5683j103 5 75,000 SH   SOLE   75,000 0 0
M & T BANK CORP COM 55261f104 634 4,095 SH   SOLE   4,095 0 0
MAGELLAN MIDSTREAM PRTNRS LP C COM 559080106 277 3,600 SH   SOLE   3,600 0 0
MARKEL CORP HLDG CO COM 570535104 93,325 95,634 SH   SOLE   95,634 0 0
MASTERCARD INC-CLASS A COM 57636Q104 56,708 504,207 SH   SOLE   504,207 0 0
MCCORMICK & CO INC COM NON VTG COM 579780206 1,282 13,139 SH   SOLE   13,139 0 0
MERCK AND CO INC SHS COM 58933y105 1,413 22,239 SH   SOLE   22,239 0 0
MESA LABS INC COM 59064R109 754 6,148 SH   SOLE   6,148 0 0
MICROSOFT CORP COM 594918104 3,534 53,658 SH   SOLE   53,658 0 0
MIDDLEBY CORP COM 596278101 2,171 15,914 SH   SOLE   15,914 0 0
MONRO MUFFLER BRAKE INC COM 610236101 930 17,855 SH   SOLE   17,855 0 0
MOODYS CORP COM 615369105 115,405 1,030,031 SH   SOLE   1,030,031 0 0
NASPERS LIMITED COM 631512100 264 15,300 SH   SOLE   15,300 0 0
NATIONAL AMERICAN UNIVER COM 63245q105 37 15,000 SH   SOLE   15,000 0 0
NATIONAL HEALTHCARE CORP COM 635906100 319 4,476 SH   SOLE   4,476 0 0
NEOGEN CORP COM COM 640491106 642 9,800 SH   SOLE   9,800 0 0
O REILLY AUTOMOTIVE INC COM 67103H107 16,278 60,324 SH   SOLE   60,324 0 0
ONEBEACON INSURANCE GROUP LTD COM G67742109 693 43,298 SH   SOLE   43,298 0 0
PAYCHEX INC COM 704326107 3,347 56,821 SH   SOLE   56,821 0 0
PEPSICO INC COM 713448108 587 5,247 SH   SOLE   5,247 0 0
PFIZER INC COM 717081103 1,054 30,818 SH   SOLE   30,818 0 0
PHILIP MORRIS INTL COM 718172109 394 3,493 SH   SOLE   3,493 0 0
PINNACLE WEST CAP CORP COM 723484101 250 3,000 SH   SOLE   3,000 0 0
PIONEER NAT RES CO COM COM 723787107 270 1,450 SH   SOLE   1,450 0 0
PNC FINCL SERVICES GROUP COM 693475105 2,156 17,934 SH   SOLE   17,934 0 0
POOL CORPORATION COM 73278l105 380 3,188 SH   SOLE   3,188 0 0
POTASH CORP SASKATCHEWAN COM 73755l107 524 30,650 SH   SOLE   30,650 0 0
PRA GROUP INC COM 69354N106 427 12,889 SH   SOLE   12,889 0 0
PRICE T ROWE GROUP INC COM 74144T108 10,592 155,420 SH   SOLE   155,420 0 0
PROCTER & GAMBLE CO COM 742718109 18,210 202,671 SH   SOLE   202,671 0 0
PROS HOLDINGS INC COM 74346Y103 56,524 2,336,673 SH   SOLE   2,336,673 0 0
QUALCOMM INC COM 747525103 22,822 398,015 SH   SOLE   398,015 0 0
RED HAT INC COM 756577102 156,002 1,803,495 SH   SOLE   1,803,495 0 0
ROPER TECHNOLOGIES INC COM 776696106 169,613 821,408 SH   SOLE   821,408 0 0
RPM INTERNATIONAL INC COM 749685103 241 4,385 SH   SOLE   4,385 0 0
S & P GLOBAL INC COM 78409V104 73,826 564,676 SH   SOLE   564,676 0 0
SBA COMMUNICATIONS CORP CL A COM 78410G104 23,427 194,627 SH   SOLE   194,627 0 0
SCHLUMBERGER LTD COM 806857108 8,143 104,258 SH   SOLE   104,258 0 0
SEI INVESTMENTS CO COM 784117103 122,900 2,436,564 SH   SOLE   2,436,564 0 0
SIGNET JEWELERS LTD COM G81276100 1,404 20,265 SH   SOLE   20,265 0 0
SITEONE COM 82982l103 218 4,493 SH   SOLE   4,493 0 0
SMITH & NEPHEW P L C ADS COM 83175M205 334 10,800 SH   SOLE   10,800 0 0
SOTHERLY HOTELS INC COM COM 83600C103 74 11,625 SH   SOLE   11,625 0 0
STERICYCLE INC COM 858912108 19,963 240,839 SH   SOLE   240,839 0 0
STERIS PLC COM G84720104 64,818 933,169 SH   SOLE   933,169 0 0
TELADOC INC COM 87918A105 1,328 53,110 SH   SOLE   53,110 0 0
TESLA INC COM 88160R101 239 857 SH   SOLE   857 0 0
TRANSDIGM GROUP INC COM 893641100 52,448 238,225 SH   SOLE   238,225 0 0
TRIMBLE INC COM 896239100 91,321 2,852,896 SH   SOLE   2,852,896 0 0
TYLER TECHNOLOGIES INC COM 902252105 94,635 612,286 SH   SOLE   612,286 0 0
U S BANCORP COM 902973304 1,632 31,686 SH   SOLE   31,686 0 0
ULTIMATE SOFTWARE GROUP INC COM 90385D107 294 1,504 SH   SOLE   1,504 0 0
UNITED PARCEL SERVICE INC CL B COM 911312106 332 3,097 SH   SOLE   3,097 0 0
UNITED TECHS CORP COM COM 913017109 466 4,152 SH   SOLE   4,152 0 0
VENTAS INC REIT COM 92276f100 1,953 30,032 SH   SOLE   30,032 0 0
VERISK ANALYTICS INC COM 92345Y106 98,228 1,210,605 SH   SOLE   1,210,605 0 0
VERIZON COMMUNICATNS COM COM 92343v104 412 8,456 SH   SOLE   8,456 0 0
VISA INC CL A COM 92826C839 128,545 1,446,443 SH   SOLE   1,446,443 0 0
W.P. CAREY INC. REIT COM 92936u109 358 5,758 SH   SOLE   5,758 0 0
WABTEC COM 929740108 83,830 1,074,742 SH   SOLE   1,074,742 0 0
WAGEWORKS INC COM 930427109 97,417 1,347,406 SH   SOLE   1,347,406 0 0
WASTE CONNECTIONS INC COM 94106B101 88,724 1,005,718 SH   SOLE   1,005,718 0 0
WATSCO INC COM COM 942622200 4,660 32,544 SH   SOLE   32,544 0 0
WAYFAIR COM 94419l101 341 8,416 SH   SOLE   8,416 0 0
WELLS FARGO & CO COM 949746101 426 7,659 SH   SOLE   7,659 0 0
WELLTOWER INC COM 95040q104 372 5,246 SH   SOLE   5,246 0 0
WHOLE FOODS MKT INC COM COM 966837106 344 11,590 SH   SOLE   11,590 0 0
WSFS FINANCIAL CORP COM 929328102 1,356 29,507 SH   SOLE   29,507 0 0
ZOE'S KITCHEN INC COM 98979J109 230 12,456 SH   SOLE   12,456 0 0
ZURICH INSURANCE GROUP-ADR COM 989825104 203 7,600 SH   SOLE   7,600 0 0
BLACKROCK ENHANCED EQT DIV TR ETFS 09251A104 85 10,000 SH   SOLE   10,000 0 0
ISHARES MSCI EAFE ETF ETFS 464287465 255 4,099 SH   SOLE   4,099 0 0
VANGUARD DIVIDEND APPREC ETFS 921908844 1,075 11,950 SH   SOLE   11,950 0 0
VANGUARD FTSE ALL WORLD EX US ETFS 922042775 2,943 61,541 SH   SOLE   61,541 0 0
VANGUARD FTSE EMERGING MARK ET ETFS 922042858 499 12,566 SH   SOLE   12,566 0 0
VANGUARD HIGH DVD YIELD ETF ETFS 921946406 791 10,186 SH   SOLE   10,186 0 0
VANGUARD INDEX FDS FORMERLY VA ETFS 922908363 4,808 22,225 SH   SOLE   22,225 0 0
VANGUARD REIT ETF ETFS 922908553 745 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 317 2,615 SH   SOLE   2,615 0 0