Standard Handbook of Petroleum and Natural Gas Engineering (3rd Edition)

Petroleum Production Engineering (2nd Edition)
 

Enhanced Oil Recovery - Resonance Macro- and Micro-Mechanics of Petroleum Reservoirs
 

Intelligent Digital Oil and Gas Fields - Concepts, Collaboration, and Right-Time Decisions

ASM Handbooks Online metals properties and processing - 25 volume set.

Knovel  2,500+ handbooks and analytical tools for topics in science and engineering.

Ebrary ebook collection covering all topics, not limited to engineering and sciencek

Synthesis Digital Library of Engineering and Computer Science - Lecture-format books, 50 to 100 pages in length (Morgan & Claypool Publishers)