access 160+ million publications and connect with 25+ million researchers. join for free and gain visibility by uploading your research.

internet archive is a non-profit digital library offering free universal access to books, movies & music, as well as 624 billion archived web pages.

sistema de información científica redalyc. red de revistas científicas. acceso abierto sin fines de lucro propiedad de la academia. modelo de acceso abierto diamante.

polytechnic university of puerto rico offers undergraduate and graduate degrees in engineering, architecture, management and secondary education. become a successful professional in one of our campuses in san juan, orlando or miami. find the program that’s right for you!

sci-hub website. get free access to academic journals. download research papers for free from sciencedirect, ieee, wiley, springer, nature and others

library genesis is a scientific community targeting collection of books on natural science disciplines and engineering.

at studycountry you can find information for students about every country in the world.