Sleuth Book for Genealogists Strategies for More Successful Family History Research Book

I feel like I already knew much of what was in this book because I have conducted my own family history/genealogy research, and helped others with theirs, for several years. It may be a good book for beginners or semi-beginners.

However, there was one piece of information I found so valuable that it's the only thing I kept a copy of: page 213 lists information on when European nations changed their calendars to the Gregorian calendar. We use the Gregorian system in our modern calendars today.