Although some have complained that this book has little to offer grizzled veterans of digital operations on the HF bands, it is an excellent primer on:
1.) what's available,
2.) what each method can and can't do, and
3.) the requirements for operating each.
This is a "handbook" in the sense of "a guide" or "a quick reference." It is not an encyclopedia, like ARRL's "Handbook of Radio Communications" or CRC's "Handbook of Chemistry and Physics," neither of which, ironically, can really be held in the hand.