At the Rumours forum Favorite Deluxe Box Sets thread I mentioned the 25 Years – The Chain box set. Disc 4 is a good introduction to the early years songs for those who were not familiar with that era (as I was). However, though it's cool they included Black Magic Woman, I think they should include I Loved Another Woman. Peter gives us a very good version of this song, that differs from the 1987 Rick Vito live version (very good one, too).
Mick talks about it in his first book.
"I Loved Another Woman," with its icy reverb and faintly Cuban beat, was a perfect example of the majestic sonic airway along which Peter was beginning to fly. This song remains a part of our concert set to this day...
in March '68 when we released Peter's new song "Black Magic Woman." Three minutes of sustain/reverb guitar with two exquisite solos from Peter, "Black Magic Woman" was descended from "I Loved Another
Woman" with one of our trademark fast twelve-bar shuffles as a coda.
https://www.youtube.com/watch?v=Rdik8L_Wxx4