Know Free is a web portal where users are able to exchange freely e-books, video training and other materials for educational purposes and self-practice http://knowfree.net/
WorldWideScience.org is a global science gateway comprised of national and international scientific databases and portals. https://worldwidescience.org/
Libdex is a worldwide directory of library homepages, web-based OPACs, Friends of the Library pages, and library e-commerce affiliate links. http://www.libdex.com/
FreePatentsOnline.com – A simple patent search database, freepatentsonline.com offers to chemical researchers a unique way of searching for patent documents. http://www.freepatentsonline.com/
