The OSF Preprints search combines records from various preprint repositories, including arXiv, bioRxiv, Cogprints, PeerJ, PsyArXiv, RePEc and SocArXiv.
zbMATH Open (formerly known as Zentralblatt MATH) is the world's most complete and longest running abstracting and reviewing service in pure and applied mathematics. The MATH Database contains several million entries drawn from more than 3,500 serials and journals, and more than 1,100 book series and monographs. The entries are classified according to the Mathematics Subject Classification Scheme (MSC 2000).