Grammars for Regular Languages: A series of pages showing that a regular grammar is either a right-linear or left-linear grammar.
Regular Expression: The formal definition of regular expressions, also used to define regular languages.
Regular Expression: A Wikipedia articele on regular expressions with an informal discussion, a formal definition and examples.
Regular Language: Basic definitions of regular languages, how they are generated, closure properties, and comparison with context free languages.
Regular Languages: This site gives a recursive definition of the class of regular languages, discusses its closure properties and gives examples.