Have read & used the 91st Psalm for many years and have been greatly blessed. This psalm is vital to live by. This book is the most thorough ever written that I have seen. I personally know a pilot that was recently saved from being killed whose wife was praying protection. A mystery storm came out of nowhere that cancelled a mission that would have cost the lives of several others. Needless to say there were some conversions. I have and am sending copies to needy people.