Wikipedia:Articles for deletion/Calendars in the Forgotten Realms
I wouldn't call this Original Research, as I'm pretty sure most of the information here can be found in various official D&D sourcebooks.  However, it certainly isn't ''notable'' either.  There are really no decent reliable, secondary sources that discuss the concept in any way that would pass the 
— User:Rorshacma, 02:11, 12 May 2020 (UTC)
Stance: delete
Cited policy: WP:GNG (Wikipedia:Notability)