It is a Maru Mechanic book. here was a whole series of them in the 70s and 80s. You can find them on Ebay occasionally. I get mine from JN online bookstores. Lots cheaper. I have the hardcopy of this book and the 1977 softcover version. Guess there were updates! I am using the hardback Maru for the Zero along with the Tamiya Zero model for my build.

Jeff