||Not listed in DeadBase XI. From the San Francisco Chronicle newspaper of Monday December 23, 1968 pg 35: "At The Matrix tonight and tomorrow night: Jerry Garcia, Jack Casady, open end jam, no door charge" and elsewhere on the same page under the heading "OPENING tODAY": "ROCK CLUB - Jam Session with Jerry Garcia, Jack Cassady and others, from 9:30 p.m., The Matrix, 3138 Fillmore. Free." on page 26 of issue #34 (Summer 1996) of Dupree's Diamond News, Dick Latvala stated in an interview "There are tapes of 12/16/68 marked Hartbeats at The Matrix, but I don't know if that's really accurate. You know (David) Crosby was playing with them quite a lot that month." He makes no other mention of 12/68 Matrix tapes in the vault.