Greetings to everyone on the list!
I’m an Italian student trying to write my dissertation about Willa Cather’s novels O Pioneers!, The Song of The Lark and My Ántonia. I need to disturb you with a question
I’ve found elsewhere the phrase “prairie trilogy”, referring the three novels, and I couldn’t trace it back to any critical work. I couldn’t just ignore it, being it so frequent (in informal writings), so I decided to address this term and explain why I think it isn’t the right term for the novels, but I need to find out its origins.
So, my question is: do you know this phrase? Have you ever tried to find out its origins? If yes, what kind of origins does it have? Any opinion about it is very welcome!
Thank you very much, 
Lavinia Moretti