Major theories of tense

Theories of temporal reference have been provided by:
 * Comrie (1985)
 * Declerck (2006)
 * Klein (1994)
 * Reichenbach (1947)
 * Huddleston and Pullum (2002)

Comparison
The theories of Reichenbach (1947), Comrie (1985), Klein (1994) and Huddleston and Pullum (2002) are based on comparable primitives