Harrington had explained the concept of evaluating tournament situations based on a range (although he didn't necessarily call it a range) in his Harrington on

Harrington had explained the concept of evaluating tournament situations based on a range (although he didn't necessarily call it a range) in his Harrington on Hold 'Em books. Galfond's gbucks article, maybe not the first mention of it, brought the concept of equity against a range into the mainstream.