I myself along with my brother have just begun taking hapkido. Our teacher recieve his black belt from the author of that book. To be honest I have searched for many books on hapkido and have found that one to be the most comprehensive. However, if i were you, I would order it on-line rather than paying full price for it at a book store.
As I said, if you really wanted to give your father a good book then look no further it really is the best out there, most other books on hapkido just display techniques, not much history on the subject. You should also look into the introduction book, it's sort of a synapse or quick review of the larger book. I believe it has a short history, it's not as extensive as the 1200 page book, it's only around 50 pages and cost $20 US.
The complete book is around $60-80. But you can get it for $40-50 on-line.
Another short little book by Tuttle Publishing is called
Hapkido: Korean Art of Self Defense by: Scott Shaw
It's a nice little book, easy reading, short historical overview, good ammount of techniques demonstrated. Cost $9.95 US.
"Poor is the pupil who
does not surpass his
master" - Leonardo Da