arXiv is an e-print service in the fields of physics, mathematics, computer science, quantitative biology, quantitative finance, statistics, electrical engineering and systems science, and economics. It provides access to more the 1.3 million e-prints. The Max Planck Society is a member institution of arXiv.

Cogitatio is an academic and community-oriented publisher based in Lisbon, which was founded in 2014 with the aim of promoting the open access dissemination of scientific knowledge. Cogitatio currently publishes 4 peer-reviewed Open Access journals focusing on research in the social sciences and humanities. From January 1, 2023, the Max Planck Society covers article-processing charges for Max Planck authors centrally. Further details are available on the MPDL website.

The OSF Preprints search combines records from various preprint repositories, including arXiv, bioRxiv, Cogprints, PeerJ, PsyArXiv, RePEc and SocArXiv.

The database POLDOK, in its current version, contains up to 40,000 documents including bibliographical metadata, subject headings and summaries about the topic "Politics of the 80ies". The retrieval system "Freitext" enables fast and convenient access to the database. Freitext was developed in the course of the BMFT project "FiSch - Fachinformation in Schulen" under the management of Prof. Dr. Robert Funk. -- Die Datenbank POLDOK enthält in der vorliegenden Fassung knapp 40.000 Dokumente mit bibliographischen Angaben, Schlagwörtern und Kurzreferaten zum Themenbereich "Politik der 80er Jahre". Das Retrievalsystem Freitext ermöglicht einen schnellen und komfortablen Suchzugriff auf die Datenbank. Freitext wurde im BMFT-Projekt "FiSch - Fachinformation in Schulen" unter der Leitung von Prof. Dr. Robert Funk entwickelt.

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).