Thomas Guide, alternately published as Thomas Brothers Maps, is the title of a series of paperback, spiral-bound atlases featuring detailed street maps of various large metropolitan areas in the United States. Thomas Guides were a local icon in Southern California for decades, with many companies including the Thomas Guide map grid information for their locations in Yellow Pages listings and other advertisements.
The Thomas Brothers were a Catholic monastic order which had many outlets in the Golden Province, including a significant one in the Barony of Orange near Angels City. The monks were great cartographers and record keepers. In 1993, EPAgentDavid Fisher consulted the Brothers for information on the history of the land where the Devonshire dump was built. Erasmus the librarian helped him.
When impersonating his younger self through time travel, Justin Kloster used a Thomas Brothers guide to keep himself informed on local geography which was second nature to his younger self but dim ancient history to his subjective mind.