Handbooks, Manuals, Source-books and Guide-books
They are handy, single volume ready reference sources on a specific subject in various forms. They handle already established knowledge. They are:
compendia of facts in shorthand form consisting of diagrams, graphs, tables, equations; formulas, procedures, principles, instructions etc.;
concise treatise of facts of popular interests;
self-instructional manuals to operate and repair machines and equipments, to cook various types of recipes, to learn languages, manners and etiquettes, to learn to play games and musical instruments, to carry forward with hobbies etc.
guides to family health and first aid;
rules for government servants; and
handbooks for historical and literary information as well as various subject specialists