"Preprint Citation Index" is now available.

■Preprint Citation Index (1991-)
Major preprint repositories are available on the Web of Science.
The current coverage is as follows.
・arXiv: physics, mathematics, computer science, quantitative biology, quantitative finance, statistics, electrical engineering and systems science, and economics
・bioRxiv: biology
・medRxiv: medicine, clinical and related health sciences
・ChemRxiv: chemistry and related fields
・Preprints（preprints.org）: interdisciplinary disciplines spanning the sciences, social sciences, and arts and humanities
*More to be added in the future.

■Use the database
Web of Science