Passage: Osbert Salvin FRS (25 February 1835 – 1 June 1898) was an English naturalist, ornithologist, and herpetologist best known for co-authoring Biologia Centrali-Americana (1879–1915) with Frederick DuCane Godman. This was a 52 volume encyclopedia on the natural history of Central America.

Question: How many different pieces were part of this work?
52