Leeuwenhoek's zoological researches. Part II. Bibliography and analytical Index.
Sorting out Leeuwenhoek's publication history is a daunting task. Until now, the best list of (almost) all of Leeuwenhoek's letters is F. J. Cole's bibliography published between Dobell's biography of 1932 and volume 1 of the Alle de Brieven / Collected Letters in 1939.
Cole F. J. Leeuwenhoek's zoological researches. Part II. Bibliography and analytical Index. Annals of Science, Volume 2, Issue 2 April 1937, pages 185 - 235.
Cole lists the letters by date, and then the bibliographic reference in one or more of four sources: Leeuwenhoek's self-published Dutch and Latin versions, the Philosophical Transactions, and finally Hoole's Select Works. Cole also lists the several dozen early letters not published anywhere, some until the late 1800's and then the "lost" fourteen in 1931 by Dobell (p. 356).
Cole notes that his article lists and indexes only letters published during Leeuwenhoek's lifetime by the Royal Society and by Leeuwenhoek himself.
More information about Cole's numbering system under Learn more: How many letters did he write?