=== References

I am grateful to the following sources.

==== Date calculations
* http://michaelthompson.org/technikos/holidays.php

==== Easter calculations
* http://www.assa.org.au/edm.html
* http://www.smart.net/~mmontes/ec-cal.html

==== World dates
* http://www.un.org/geninfo/faq/factsheets/FS18.HTM
* http://en.wikipedia.org/wiki/List_of_holidays_by_country