Many say the VERY best book on prayer (other than the Word) is “Rees Howells, Intercessor” by Norman Grubb.
If you’re serious about Learning About Prayer, get this book.
BTW: thru this man’s prayers (and those of his Bible students) the course of World War 2 was changed!
Yes,I agree. That book is the best,,,really amazing what the Lord did through that group of intercessors.