Again the Pacific Poultryman's Magazine, January 1921.
This was a good reminder to plant the Winter Clover while it is still warm. Last year we did it far too late, around November 1st and it was brutal sowing the seeds and scratching in the dirt -- most which was almost frozen.
I got my seeds from Johnny's Seeds up in Maine and used their seed calculator too. According to the USDA hardiness tables, recently redone, we are in 5A.