1. An important and valuable guide to the scientific work of Van Leeuwenhoek has been published by Clifford Dobell (1932), Amony van Leeuwenhoek and his ‘Little Animals’ , John Bale, Sons and Danielsson, London (reprinted Dover Publications, New York, 1960). Here will be found a guide to the many publications, in Dutch or Latin, of Leeuwenhoek's letters (pp. 388-397). Some letters or extracts have been translated by Dobell and are printed in his book. A work that can be found in a number of libraries is Opera Omnia, seu Arcana Naturae, ope Exactissimorum Microscopiorum Detecta, experimentis variis comprobata, Epistolis, ad varios illustres Viros , … 4 vols, J. A. Langerak, Leyden, 1722. This contains letters numbered 28-146 and I-XLVI. Leeuwenhoek numbered his published letters in chronological order in two series, but began with No. 28 and not with No. 1. The Royal Society of London has about 200 manuscript letters, and these are referred to by Dobell in a numbered sequence beginning at No. 1. A complete edition of Leeuwenhoek's letters is in progress under the auspices of the Leeuwenhoek Commission of the Royal Netherlands Academy of Sciences and Letters. In this edition, which includes all the letters in the original Dutch together with a modern translation into English, the letters are numbered strictly in chronological order
2. The letters are referred to here by the number in this edition, and by the date and the addressee; see The Collected Letters of Antoni van Leeuwenhoek, edited, illustrated and annotated by a Committee of Dutch Scientists , …, vols. 1-8, Amsterdam, 1939-67. Leeuwenhoek's own numbers, as, for example, in Opera Omnia , are given in square brackets
3. An account of Mr. Leeuwenhoek's microscopes;Baker;Phil. Trans.,1741