zbMATH Open"Currently, zbMATH Open contains around 4.4 million bibliographic entries with reviews or abstracts drawn from more than 3,000 journals and book series, and some 190,000 books. Our coverage, which starts in the 18th century, is complete from 1868 to the present day, due to the integration of the 'Jahrbuch über die Fortschritte der Mathematik' database."