Book data collected from the following digital collections

Bibliothèque nationale de France - collection Gallica	Documents (736)
Cornell University Library - Digital Math Books Collection	Documents (504)
Michigan University Library - Making of America	Documents (45)
Michigan University Library - Historical Math Collection	Documents (772)
Göttinger Digitalisierungszentrum - Mathematica	Documents (536)
ICM, Uniwersytet Warszawski - Biblioteka Wirtualna Matematyki	Documents (39)
AMS Books Online	Documents (34)
Universität Bielefeld	Documents (9)
Strasbourg SICD	Documents (139)
Pôlib Lille	Documents (2)
NUMIX - École Polytechnique	Documents (4)
Biblioteca Nacional Digital (Lisbonne)	Documents (1)
MSRI books	Documents (28)