[Discover] Java date and time API - Home - Joda Time http://joda-time.sourceforge.net/
(java date time library) 
[Discover] timeanddate.com http://www.timeanddate.com/ (reference tools calendar date)
[Discover] Relational algebra - Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/Relational_algebra#Natural_join (date codd relational sql)
[Discover] InfoQ: Writing A Textual DSL Using 'OSLO' http://www.infoq.com/articles/natural-language-date-dsl-oslo (date time datetime dsl)
[Discover] timeanddate.com http://www.timeanddate.com/ (reference tools calendar date)
[Discover] Relational algebra - Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/Relational_algebra#Natural_join (date codd relational sql)
[Discover] InfoQ: Writing A Textual DSL Using 'OSLO' http://www.infoq.com/articles/natural-language-date-dsl-oslo (date time datetime dsl)