| http://archive.lib.msu.edu/tic/monos/LawnsandHow19[...] | 03/26/2019 | PDF Reader | | |
| https://babel.hathitrust.org/cgi/pt?id=hvd.3204402[...] | 03/26/2019 | JavaScript | Possibly USA access only | |
| https://books.google.com/books?id=wjUAAAAAYAAJ&pri[...] | 03/26/2019 | | | |
| http://edepot.wur.nl/273836 | 03/26/2019 | PDf Reader | | |
| http://babel.hathitrust.org/cgi/pt?id=uc2.ark:/139[...] | 03/26/2019 | JavaScript | Possibly USA access only | 1909 reprint |
| https://babel.hathitrust.org/cgi/pt?id=hvd.3204402[...] | 03/26/2019 | JavaScript | Possibly USA access only | 1910 reprint |
| https://books.google.com/books?id=nzUAAAAAYAAJ&pri[...] | 03/26/2019 | | | 1910 reprint |
| http://www.biodiversitylibrary.org/title/54759#pag[...] | 03/26/2019 | JavaScript | | 1914 reprint |
| http://archive.org/details/cu31924089539070 | 03/26/2019 | JavaScript | | 1914 reprint |
| https://books.google.com/books?id=aAs_AQAAMAAJ&pri[...] | 03/26/2019 | | | 1914 reprint |
