Use the CRAAP Test
Currency - Is it timely?
Relevance - Useful for your purposes?
Authority - Who? What is the source?
Accuracy - References to back it up?
Purpose - Why? Is there a bias?
More detailed information on the CRAAP Test
Mathematical and Statistical Sciences Databases
This is the world's most comprehensive and longest-running abstracting and reviewing service in pure and applied mathematics. The extensive book and journal 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.
arXiv.org is an electronic archive and distribution server for open access research papers in Physics, Astronomy, Mathematics, Computer Science, Quantitative Biology and Statistics.
Interdisciplinary Databases