users explore patterns in scientific research, identify literature trends, discover collaborative relationships, and locate experts in several scientific/medical fields. Springer Protocols contained a collection of laboratory protocols, recipes that provide step-by-step instructions for conducting experiments, which in 2018 was made available in SpringerLink instead. Book publications include major reference works, textbooks, monographs and book series; more than 168,000 titles are available as e-books in 24 subject collections. Open access Springer is a member of the Open Access Scholarly Publishers Association. For some of its journals, Springer does not require its authors to transfer their copyrights, and allows them to decide whether their articles are published under an open-access license or in the traditional restricted licence model. While open-access publishing typically requires the author to pay a fee for copyright retention, this fee is sometimes covered by a third party. For example, a national institution in Poland allows authors to publish in open-access journals without incurring any personal cost but using public funds. Controversies In 1938, Springer-Verlag insisted that the journal Zentralblatt MATH adhere to Nazi principles. Tullio Levi-Civita, who was Jewish, was forced from the editorial board, and Otto Neugebauer resigned in protest along with most of the rest of the board. In 2014, it was revealed that 16 papers in conference proceedings published by Springer had been computer-generated using SCIgen. Springer subsequently retracted all papers from these proceedings. IEEE had removed more than 100 fake papers from its conference proceedings. In 2015, Springer retracted 64 papers from 10 of its journals it had published after a fraudulent peer review process was uncovered. Manipulation of bibliometrics According to Goodhart's law and concerned academics like the signatories of the San Francisco Declaration on Research Assessment, commercial academic publishers benefit from manipulation of bibliometrics and scientometrics like the journal impact factor, which is often used as a proxy of prestige and can influence revenues, including public subsidies in the form of subscriptions and free work from academics. Seven Springer Nature journals, which exhibited unusual levels of self-citation, had their journal impact factor of 2019 suspended from Journal Citation Reports in 2020, a sanction which hit 34 journals in total. Selected imprints Adis International Apress BioMed Central Chemistry Central (defunct) PhysMath Central (defunct) Birkhäuser Verlag Current Medicine Group Humana Press Infochem Kluwer Academic Publishers D. Reidel (defunct) Plenum Publishers SpringerOpen Springer Gabler Springer Praxis Books (formerly (SAV)) Springer Vieweg Selected publications Encyclopaedia of