Additional info is available all over the web. A few sources follow. Direct links are not provided on some as some sites requeste this: A simple search using the BOLD text will find them.
USMC Summer Survival Course Handbook: Available as a pdf file loaded with proven information.
Project Gutenberg: A good site with Thousands of free books including :
Deadfalls and Snares, by A. R. (Arthur Robert) Harding - A Book of Instruction forTrappers About These and Other Home-Made Traps
Russian Aircrew Survival Manual: A scanned manual on ruspace (Instruction No.1907-2670) Look under fishing and also snares and traps for pics.
USMC Winter Survival Course Handbook: Available as a pdf file loaded with proven information.
Knots by Andrew Adamides: Might be worth buying the book.