Thej

@ainvvy @rags2rama “History of Calendar” by Saha Meghnad and Lahiri ( Calendar Reform Committee) discuss this in detail. Not modern but good one.

https://archive.org/details/historyofcalendarindifferentcountriesthroughdifferentagessham.n.laharin.c._926_u

They also fixed this and released Indian national calendar. Which is used currently used by Gazette