The list of Latvian holidays (day offs) and commemoration days.
Information sources:
Replace holidays:
(setq calendar-holidays latvian-holidays)
Or append holidays:
(setq calendar-holidays (append calendar-holidays latvian-holidays))
You could also append commemoration and celebration days:
(setq calendar-holidays (append latvian-holidays latvian-holidays-commemoration-days))
or:
(setq calendar-holidays (append calendar-holidays latvian-holidays latvian-holidays-commemoration-days))