I’m very late in discovering this, but the hardback compilation Mouse Guard: The Black Axe is a must-have for all readers of the Mouse Guard comics (David Petersen, published by Archaia) and especially for players of the role-playing game based on the comic, the Mouse Guard RPG (Luke Crane & David Petersen).
It’s full of information about what the Guard Mice do, the art is as inspiring as ever, and the book offers a nice appendix full of maps, illustrations of locations, genealogies of famous mouse clans, etc. (You can see examples of location art here, but the ones in the book are different and contain much more information.)
The Reef 