Although this compilation came out in the mid-sixties, the recordings are all from 1954-1957.

Thanks to the Gerry Mulligan Discography compiled by Antoine Perier, Gérard Dugely, and Kenneth Hallqvist, they would seem to be:

• Storyville Club, Boston, Massachusetts, December 1-6, 1956 (A1, A2, A3, A5, B3)
• Salle Pleyel, Paris, France, June 7th, 1954 (last evening concert) (A4, B2)
• Coastal Studios, New York City, NY. December 4 & 5, 1957 (B1, B5)
• Stockton High School, Stockton, CA, November 12, 1954 (B4)

My copy is a Canadian pressing via Aux 33 Tours in Montreal, QC