Here are few IT books in PDF format that you may find useful.

Data Structures and Algorithms pdf
Data Structures and Algorithms: Annotated Reference with Examples
First Edition
Granville Barnett, Luca Del Tono
Data Comm and Networking pdf
Data Communications and Networking
Fifth Edition
Behrouz A.Forouzan
Learning Python pdfLearning Python
Fifth Edition
Mark Lutz
Database system Concepts pdfDatabase System Concepts
Sixth Edition
Abraham Silberschatz, Henry F.Korth, S.Sudarshan
Designing IOT pdf
Designing the Internet of Things
Adrian McEwen, Hakim Cassimally
Java2EE pdf
The J2EE 1.4 Tutorial - 8.2
Eric Armstrong, Jennifer Ball, Stephanie Bodoff, Debbie Bode Carson
Ian Evans, Dale Green, Kim Haase, Eric Jendrock
getting started with raspberry pi pdf
Getting Started with Raspberry Pi
Matt Richardson, Shawn Wallace