"and not to forget the Almanac"

Example of an Almanac
Public DomainExample of an Almanac - Credit: Boston Daily Advertiser
In the story, Loew's Nominative Almanac is a book that lists all official names used by magicians between Prague's golden age and the present. It is used during a magician's official Naming Ceremony. Nathaniel will have to choose a name from the almanac, after checking that it is not presently in use