The Research Disclosure database is a superb on-line tool for both patentability and validity searches
The entire Research Disclosure archive is available online. All records are full text searchable and include the complete original disclosure.
Research Disclosure has been the industry standard disclosure service for over 50 years. Over that period the service has been used by an estimated 90% of the world's leading companies and has grown into one of the most significant archives of non-patent literature available.