Only available direct from Vickers Guide:
https://www.vickersguide.com/hk-vol1-1

The Vickers Guide series of books by Larry Vickers and James Rupley began as beautifully photographed firearms art books - and that's all they claim to be today. However, with the release of Heckler & Koch Volume 1, the series is doing something really cool: it's leaning into the reference/research realm without compromising its artistic vision. This book includes a third coauthor, James Williamson of Teufelhund Tactical. Between him and Vickers, this book has a remarkable amount of detailed information about the history and development of H&K handguns.

Hanguns, I should say, are the subject of this volume - SMGs and long guns will apparently be covered in Volumes 2 and 3 (yet to be published). Here we start with the HK4 (essentially an improved version of the Mauser HSc), move through H&K's classic non-Browning action designs like the VP70, P7, and P9, and then into the USP series. The Mk 23 is covered in its own specific chapter, and the modern H&K commercial pistols are explored in detail as well (P2000, VP9, P30). The development of the HK45 is also covered in detail, as Larry Vickers was heavily involved in that program.

Frankly, I wish I'd had this book available when I was filming some of my older H&K handgun videos. It has more information than most of the reference books out there, and is an excellent resource for better understanding how H&K has approached the handgun market and handgun design.