It is only available from the Harvard Law Library. It is part of the Lotta Crabtree Will Case. I spent several days at the Law library researching the case. Dr. Giberson was the doctor who took care of Jack Crabtree's child, hence his testimony. What I quoted was all he said about the street fight.
Dr. Giberson was a pretty interesting guy being he "stole" Lyttleton Price's wife. I wrote an article about it for Wild West a few years ago titled: Tombstone Love Triangle.