Conversation so far:
What artists did John Denver work with?
Denver began his recording career with a group that had started as the Chad Mitchell Trio.
Who was in the group?
The group Denver, Boise, and Johnson, which had evolved from the Mitchell Trio.
Did they record any albums?
He recorded three albums with the Mitchell Trio.
what songs were on there?
his distinctive voice can be heard where he sings solo on Violets of Dawn, among other songs.

Question: did he work with anyone else?
Self-contained rewrite: Besides the Chad Mitchell trio did John Denver work with anyone else?