for books the below link/site can help you:

Library Genesis

http://gen.lib.rus.ec/

Thank you Zahid for your information

Dear P. Preethalayam

You can add the name of each book do you want to Utorrent (the book+utorrent) and search it in a search engine. You probably would be able to download every book do you want using this website.

I hope it helps you.

sincerely regards

K. Kohansal

Thank you Kohansal for your information...

The 30 Best Websites for Downloading Free eBooks - 1stWebDesigner

https://1stwebdesigner.com/ebook-download-sites/

https://open.umn.edu/opentextbooks/textbooks/introductory-chemistry

https://www.pdfdrive.com/

You can download any of the research or presentations through the correct search method, which includes the short title and ends with a comma and then a PDF or the presentations we write the end of the title of the short PPT, this method will allow you to download many of the research and offers available on the Internet

@sci-hub.tw/

Thank you all for your suggestions...

I need this book please

Houben-Weyl Methods of Organic Chemistry Vol. E 9d, 4th

http://gen.lib.rus.ec/search.php?req=Houben-Weyl+Methods+of+Organic+Chemistry&lg_topic=libgen&open=0&view=simple&res=25&phrase=1&column=def

USE THIS LINK

thank you with best wishes