Genre: "Reference" Books
A reference, is derived from Middle English referren, from Middle French rèférer, from Latin referre, "to carry back" formed from a prefix re- and ferre, "to bear". A large number of words derive from this root, including referee, reference, referendum, all retaining the basic meaning of the original Latin as "a point, place or source of origin" that something of comparable nature can be defined in terms of. A referee is the provider of this source of origin, and a referent is the possessor of the source of origin, whether it is knowledge, matter or energy.
Because of its meaning, the word reference is use in every sphere of human knowledge, adopting shades of meaning particular to the contexts in which it is used.
A references can take on many forms, including: a thought, a sensory perception that is audible (onomatopoeia), visual (text), olfactory, or tactile, emotional state, relationship with other, spacetime coordinate, symbolic or alpha-numeric, a physical object or an energy projection; but, other concrete and abstract contexts exist as methods of defining references within the scope of the various fields that require an origin, point of departure, or an original form. This includes methods that intentionally hide the reference from some observers, as in cryptography.
The following sections give specific usages of reference in different subjects.