OPEN SOURCE e-BOOKS LINKS
https://www.pdfdrive.com/category/5
https://bookboon.com/en/it-programming-ebooks
https://notesvarsity.com
https://archive.org
https://drive.google.com/drive/folders/0ByWO0aO1eI_MN1BEd3VNRUZENkU?direction=a