Volumes 1 through 20 of Alle de Brieven / Collected Letters, the complete series. Download for free.
Master list (pdf) of all 602 L-numbers, their Leeuwenhoek number, and their Collected Letters number
niece Maria Elsevier, living on the Verwersdijk, married Jan Strick, from den Haag.
DTB Delft inv. 127, fol. 24