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 742 55,863 SH   SOLE   55,863 0 0
3M COMPANY COM 88579y101 717 4,014 SH   SOLE   4,014 0 0
AAC HOLDINGS INC COM 000307108 7,677 1,060,399 SH   SOLE   1,060,399 0 0
ABBOTT LABORATORIES COM 002824100 434 11,288 SH   SOLE   11,288 0 0
ABBVIE INC SHS COM 00287y109 490 7,821 SH   SOLE   7,821 0 0
ALIGN TECHNOLOGY INC COM COM 016255101 1,967 20,464 SH   SOLE   20,464 0 0
ALPHABET INC CLASS C COM 02079K107 78,984 102,335 SH   SOLE   102,335 0 0
ALPHABET INC. CLASS A COM 02079k305 668 843 SH   SOLE   843 0 0
AMAZON.COM INC COM 023135106 47,929 63,917 SH   SOLE   63,917 0 0
AMERICAN TOWER REIT INC COM 03027X100 76,612 724,939 SH   SOLE   724,939 0 0
AMETEK INC NEW COM COM 031100100 877 18,042 SH   SOLE   18,042 0 0
AMGEN INC COM PV $0.0001 COM 031162100 222 1,515 SH   SOLE   1,515 0 0
AMPHENOL CORP NEW CL A COM 032095101 1,680 25,000 SH   SOLE   25,000 0 0
ANSYS INC COM 03662Q105 127,199 1,375,277 SH   SOLE   1,375,277 0 0
APPLE INC COM 037833100 688 5,941 SH   SOLE   5,941 0 0
APPLIED MINERALS INC COM 03823m100 9 80,000 SH   SOLE   80,000 0 0
ATRION CORPORATION COM 049904105 4,985 9,829 SH   SOLE   9,829 0 0
AUTOMATIC DATA PROC COM 053015103 2,272 22,106 SH   SOLE   22,106 0 0
BARD C R INC COM COM 067383109 1,464 6,515 SH   SOLE   6,515 0 0
BEACON ROOFING SUPPLY INC COM 073685109 238 5,161 SH   SOLE   5,161 0 0
BECTON DICKINSON&CO COM 075887109 288 1,741 SH   SOLE   1,741 0 0
BERKLEY W R CORP COM 084423102 3,163 47,558 SH   SOLE   47,558 0 0
BERKSHIRE HATHAWAY INC DELAWA COM 084670108 1,465 6 SH   SOLE   6 0 0
BERKSHIRE HATHAWAYINC DEL CL COM 084670702 3,418 20,972 SH   SOLE   20,972 0 0
BIO-TECHNE CORP COM 09073M104 37,714 366,756 SH   SOLE   366,756 0 0
BLACKBAUD INC COM 09227Q100 64,771 1,012,043 SH   SOLE   1,012,043 0 0
BLACKLINE COM 09239b109 1,969 71,260 SH   SOLE   71,260 0 0
CALAVO GROWERS INC COM 128246105 274 4,470 SH   SOLE   4,470 0 0
CAMPBELL SOUP CO COM COM 134429109 242 4,000 SH   SOLE   4,000 0 0
CANADIAN NATL RY CO COM COM 136375102 1,348 20,000 SH   SOLE   20,000 0 0
CAPITAL ONE FINL CORP COM COM 14040H105 2,112 24,204 SH   SOLE   24,204 0 0
CARMAX INC COM 143130102 105,625 1,640,394 SH   SOLE   1,640,394 0 0
CBRE GROUP INC COM 12504L109 27,818 883,379 SH   SOLE   883,379 0 0
CELGENE CORP COM 151020104 102,412 884,766 SH   SOLE   884,766 0 0
CERNER CORP COM COM 156782104 1,211 25,555 SH   SOLE   25,555 0 0
CHEVRON CORP COM 166764100 762 6,477 SH   SOLE   6,477 0 0
CHIPOTLE MEXICAN GRILL CL A COM 169656105 275 730 SH   SOLE   730 0 0
CHURCH & DWIGHT INC COM COM 171340102 1,108 25,068 SH   SOLE   25,068 0 0
CISCO SYSTEMS INC COM COM 17275r102 2,094 69,296 SH   SOLE   69,296 0 0
COCA COLA COM COM 191216100 1,033 24,914 SH   SOLE   24,914 0 0
COGNIZANT TECHNOLOGY SOLUTIONS COM 192446102 1,370 24,452 SH   SOLE   24,452 0 0
COLGATE-PALMOLIVE CO COM 194162103 649 9,925 SH   SOLE   9,925 0 0
COMCAST CORP NEW CL A COM 20030n101 4,127 59,768 SH   SOLE   59,768 0 0
COMPUTER MODELLING LTD COM 205249105 125 18,465 SH   SOLE   18,465 0 0
CORELOGIC INC COM 21871D103 357 9,704 SH   SOLE   9,704 0 0
COSTAR GROUP INC COM 22160N109 81,019 429,834 SH   SOLE   429,834 0 0
CROWN CASTLE REIT INC SHS COM 22822v101 5,763 66,413 SH   SOLE   66,413 0 0
DEXCOM INC COM 252131107 539 9,035 SH   SOLE   9,035 0 0
DISCOVER FINANCIAL SERVICES (U COM 254709108 51,612 715,932 SH   SOLE   715,932 0 0
DISNEY (WALT) CO COM STK COM 254687106 912 8,747 SH   SOLE   8,747 0 0
DOUGLAS DYNAMICS INC COM 25960R105 1,741 51,735 SH   SOLE   51,735 0 0
DU PONT EI DE NEMOUR COM 263534109 332 4,523 SH   SOLE   4,523 0 0
DUKE REALTY CORP REIT COM 264411505 355 13,350 SH   SOLE   13,350 0 0
DULUTH HOLDINGS INC COM 26443V101 1,581 62,255 SH   SOLE   62,255 0 0
EAST WEST BANCORP INC COM 27579r104 2,335 45,928 SH   SOLE   45,928 0 0
ECOLAB INC COM 278865100 124,514 1,062,225 SH   SOLE   1,062,225 0 0
ELI LILLY & CO COM 532457108 614 8,353 SH   SOLE   8,353 0 0
ELLIE MAE INC COM 28849P100 4,392 52,482 SH   SOLE   52,482 0 0
EMERSON ELECTRIC CO COM 291011104 514 9,215 SH   SOLE   9,215 0 0
ENTERPRISE PRDTS PRTN LPL P COM 293792107 464 17,175 SH   SOLE   17,175 0 0
ENVESTNET INC COM 29404K106 50,195 1,423,966 SH   SOLE   1,423,966 0 0
EQUITY RESIDENTIAL REIT COM 29476l107 388 6,026 SH   SOLE   6,026 0 0
EVERTEC INC COM 30040P103 191 10,753 SH   SOLE   10,753 0 0
EXPONENT INC COM 30214U102 30,315 502,730 SH   SOLE   502,730 0 0
EXPRESS SCRIPTS HLDG COM 30219g108 1,097 15,941 SH   SOLE   15,941 0 0
EXXON MOBIL CORP COM COM 30231g102 1,900 21,046 SH   SOLE   21,046 0 0
FASTENAL CO COM 311900104 87,295 1,858,135 SH   SOLE   1,858,135 0 0
FISERV INC COM 337738108 9,934 93,467 SH   SOLE   93,467 0 0
FORTINET INC COM COM 34959E109 430 14,263 SH   SOLE   14,263 0 0
GENERAL ELECTRIC COM 369604103 3,704 117,200 SH   SOLE   117,200 0 0
GENUINE PARTS CO COM 372460105 476 4,984 SH   SOLE   4,984 0 0
GOOD TIMES RESTAURANTS INC COM 382140879 123 38,928 SH   SOLE   38,928 0 0
GUIDEWIRE SOFTWARE INC COM 40171V100 584 11,833 SH   SOLE   11,833 0 0
HCP INC COM 40414l109 1,810 60,903 SH   SOLE   60,903 0 0
HEALTHCARE SERVICES GROUP INC COM 421906108 64,888 1,656,571 SH   SOLE   1,656,571 0 0
HEICO CORP NEW CL A COM 422806208 400 5,885 SH   SOLE   5,885 0 0
HOME DEPOT INC COM 437076102 363 2,708 SH   SOLE   2,708 0 0
IBM CORP COM 459200101 1,244 7,492 SH   SOLE   7,492 0 0
IDEXX LABORATORIES INC COM 45168D104 14,419 122,959 SH   SOLE   122,959 0 0
ILLINOIS TOOL WORKS COM 452308109 251 2,050 SH   SOLE   2,050 0 0
ILLUMINA INC COM 452327109 64,773 505,883 SH   SOLE   505,883 0 0
IMAX CORP COM 45245E109 94,023 2,994,349 SH   SOLE   2,994,349 0 0
INTEL CORP COM 458140100 12,574 346,689 SH   SOLE   346,689 0 0
INTERCONTINENTAL EXCHANGE INC COM 45866F104 1,804 31,980 SH   SOLE   31,980 0 0
INTUIT COM COM 461202103 1,955 17,054 SH   SOLE   17,054 0 0
INTUITIVE SURGICAL INC COM 46120E602 101,663 160,309 SH   SOLE   160,309 0 0
INVENTURE FOODS INC COM 461212102 285 28,902 SH   SOLE   28,902 0 0
JOHN BEAN TECHNOLOGIES COM 477839104 224 2,601 SH   SOLE   2,601 0 0
JOHNSON AND JOHNSON COM COM 478160104 10,214 88,659 SH   SOLE   88,659 0 0
JPMORGAN CHASE & CO COM 46625h100 440 5,104 SH   SOLE   5,104 0 0
KIMBERLY CLARK COM 494368103 271 2,373 SH   SOLE   2,373 0 0
LABORATORY CORP AMER HLDGS COM COM 50540R409 2,338 18,213 SH   SOLE   18,213 0 0
LINCOLN NTL CORP IND NPV COM 534187109 332 5,017 SH   SOLE   5,017 0 0
LITHIA MOTORS INC CL A COM 536797103 395 4,080 SH   SOLE   4,080 0 0
LKQ CORP COM 501889208 150,339 4,905,034 SH   SOLE   4,905,034 0 0
LYNAS CORP LTD AUD PA COM q5683j103 4 75,000 SH   SOLE   75,000 0 0
M & T BANK CORP COM 55261f104 651 4,164 SH   SOLE   4,164 0 0
MAGELLAN MIDSTREAM PRTNRS LP C COM 559080106 272 3,600 SH   SOLE   3,600 0 0
MARKEL CORP HLDG CO COM 570535104 90,068 99,578 SH   SOLE   99,578 0 0
MASTERCARD INC-CLASS A COM 57636Q104 55,478 537,322 SH   SOLE   537,322 0 0
MCCORMICK & CO INC COM NON VTG COM 579780206 1,095 11,733 SH   SOLE   11,733 0 0
MERCK AND CO INC SHS COM 58933y105 1,309 22,239 SH   SOLE   22,239 0 0
MESA LABS INC COM 59064R109 525 4,281 SH   SOLE   4,281 0 0
MICROSOFT CORP COM 594918104 3,396 54,658 SH   SOLE   54,658 0 0
MIDDLEBY CORP COM 596278101 1,802 13,988 SH   SOLE   13,988 0 0
MONRO MUFFLER BRAKE INC COM 610236101 983 17,178 SH   SOLE   17,178 0 0
MOODYS CORP COM 615369105 103,063 1,093,275 SH   SOLE   1,093,275 0 0
NASPERS LTD-N SHS SPON ADR COM 631512100 422 24,800 SH   SOLE   24,800 0 0
NATIONAL AMERICAN UNIVER COM 63245q105 29 15,000 SH   SOLE   15,000 0 0
NATIONAL HEALTHCARE CORP COM 635906100 260 3,434 SH   SOLE   3,434 0 0
NEOGEN CORP COM COM 640491106 647 9,800 SH   SOLE   9,800 0 0
O REILLY AUTOMOTIVE INC COM 67103H107 18,284 65,674 SH   SOLE   65,674 0 0
ONEBEACON INSURANCE GROUP LTD COM G67742109 708 44,093 SH   SOLE   44,093 0 0
PAYCHEX INC COM 704326107 3,368 55,324 SH   SOLE   55,324 0 0
PEPSICO INC COM 713448108 549 5,247 SH   SOLE   5,247 0 0
PFIZER INC COM 717081103 1,046 32,202 SH   SOLE   32,202 0 0
PHILIP MORRIS INTL COM 718172109 311 3,403 SH   SOLE   3,403 0 0
PINNACLE WEST CAP CORP COM 723484101 234 3,000 SH   SOLE   3,000 0 0
PIONEER NAT RES CO COM COM 723787107 261 1,450 SH   SOLE   1,450 0 0
PNC FINCL SERVICES GROUP COM 693475105 2,122 18,144 SH   SOLE   18,144 0 0
POOL CORPORATION COM 73278l105 333 3,188 SH   SOLE   3,188 0 0
POTASH CORP SASKATCHEWAN COM 73755l107 2,176 120,314 SH   SOLE   120,314 0 0
PRA GROUP INC COM 69354N106 28,949 740,383 SH   SOLE   740,383 0 0
PRICE T ROWE GROUP INC COM 74144T108 11,692 155,354 SH   SOLE   155,354 0 0
PROCTER & GAMBLE CO COM 742718109 17,766 211,300 SH   SOLE   211,300 0 0
PROS HOLDINGS INC COM 74346Y103 43,520 2,022,305 SH   SOLE   2,022,305 0 0
QUALCOMM INC COM 747525103 35,514 544,695 SH   SOLE   544,695 0 0
QUALITY CARE PROPERTIES COM 747545101 160 10,340 SH   SOLE   10,340 0 0
RED HAT INC COM 756577102 122,412 1,756,276 SH   SOLE   1,756,276 0 0
REXNORD CORP COM 76169B102 201 10,281 SH   SOLE   10,281 0 0
ROPER TECHNOLOGIES INC COM 776696106 156,905 857,029 SH   SOLE   857,029 0 0
RPM INTERNATIONAL INC COM 749685103 221 4,100 SH   SOLE   4,100 0 0
S & P GLOBAL INC COM 78409V104 62,336 579,651 SH   SOLE   579,651 0 0
SBA COMMUNICATIONS CORP CL A COM 78410G104 19,988 193,565 SH   SOLE   193,565 0 0
SCHLUMBERGER LTD COM 806857108 8,878 105,757 SH   SOLE   105,757 0 0
SEI INVESTMENTS CO COM 784117103 125,985 2,552,370 SH   SOLE   2,552,370 0 0
SIGNATURE BK NEW YORK N Y COM COM 82669G104 1,673 11,140 SH   SOLE   11,140 0 0
SIGNET JEWELERS LTD COM G81276100 75,942 805,660 SH   SOLE   805,660 0 0
SMITH & NEPHEW P L C ADS COM 83175M205 325 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 241 3,455 SH   SOLE   3,455 0 0
STERICYCLE INC COM 858912108 45,929 596,172 SH   SOLE   596,172 0 0
STERIS PLC COM G84720104 50,264 745,874 SH   SOLE   745,874 0 0
TELADOC INC COM 87918A105 1,372 83,143 SH   SOLE   83,143 0 0
TESLA INC COM 88160R101 208 975 SH   SOLE   975 0 0
TRACTOR SUPPLY COMP COM 892356106 1,431 18,877 SH   SOLE   18,877 0 0
TRANSDIGM GROUP INC COM 893641100 63,721 255,949 SH   SOLE   255,949 0 0
TRIMBLE INC COM 896239100 90,487 3,001,213 SH   SOLE   3,001,213 0 0
TYLER TECHNOLOGIES INC COM 902252105 91,743 642,596 SH   SOLE   642,596 0 0
U S BANCORP COM 902973304 1,628 31,686 SH   SOLE   31,686 0 0
ULTIMATE SOFTWARE GROUP INC COM 90385D107 296 1,622 SH   SOLE   1,622 0 0
UNDER ARMOUR INC COM 904311107 669 26,580 SH   SOLE   26,580 0 0
UNDER ARMOUR INC SHS WHEN I COM 904311206 770 30,299 SH   SOLE   30,299 0 0
UNITED PARCEL SERVICE INC CL B COM 911312106 268 2,342 SH   SOLE   2,342 0 0
UNITED TECHS CORP COM COM 913017109 462 4,210 SH   SOLE   4,210 0 0
VENTAS INC REIT COM 92276f100 1,915 30,632 SH   SOLE   30,632 0 0
VERISK ANALYTICS INC COM 92345Y106 103,022 1,269,208 SH   SOLE   1,269,208 0 0
VERIZON COMMUNICATNS COM COM 92343v104 370 6,931 SH   SOLE   6,931 0 0
VISA INC CL A COM 92826C839 120,516 1,544,678 SH   SOLE   1,544,678 0 0
W.P. CAREY INC. REIT COM 92936u109 339 5,736 SH   SOLE   5,736 0 0
WABTEC COM 929740108 63,644 766,611 SH   SOLE   766,611 0 0
WAGEWORKS INC COM 930427109 112,424 1,550,676 SH   SOLE   1,550,676 0 0
WASTE CONNECTIONS INC COM 94106B101 82,396 1,048,425 SH   SOLE   1,048,425 0 0
WATSCO INC COM COM 942622200 1,975 13,332 SH   SOLE   13,332 0 0
WAYFAIR COM 94419l101 533 15,205 SH   SOLE   15,205 0 0
WELLS FARGO & CO COM 949746101 422 7,659 SH   SOLE   7,659 0 0
WELLTOWER INC COM 95040q104 351 5,246 SH   SOLE   5,246 0 0
WHOLE FOODS MKT INC COM COM 966837106 357 11,590 SH   SOLE   11,590 0 0
WSFS FINANCIAL CORP COM 929328102 1,341 28,927 SH   SOLE   28,927 0 0
ZOE'S KITCHEN INC COM 98979J109 309 12,881 SH   SOLE   12,881 0 0
ZURICH INSURANCE GROUP-ADR COM 989825104 210 7,600 SH   SOLE   7,600 0 0
BLACKROCK ENHANCED EQT DIV TR ETFS 09251A104 81 10,000 SH   SOLE   10,000 0 0
ISHARES MSCI EAFE ETF ETFS 464287465 216 3,749 SH   SOLE   3,749 0 0
VANGUARD DIVIDEND APPREC ETFS 921908844 989 11,616 SH   SOLE   11,616 0 0
VANGUARD FTSE ALL WORLD EX US ETFS 922042775 2,684 60,762 SH   SOLE   60,762 0 0
VANGUARD FTSE EMERGING MARK ET ETFS 922042858 444 12,400 SH   SOLE   12,400 0 0
VANGUARD HIGH DVD YIELD ETF ETFS 921946406 652 8,601 SH   SOLE   8,601 0 0
VANGUARD INDEX FDS FORMERLY VA ETFS 922908363 3,754 18,285 SH   SOLE   18,285 0 0
VANGUARD REIT ETF ETFS 922908553 744 9,015 SH   SOLE   9,015 0 0
VANGUARD SHORT-TERM GOV BD ETFS 92206c102 440 7,225 SH   SOLE   7,225 0 0
VANGUARD TOTAL STK MKT ETF ETFS 922908769 302 2,615 SH   SOLE   2,615 0 0