A. Bruce Frederick has been one of the most prolific gymnastics authors.
Now retired, he still maintains an interesting site called Roots of American Gymnastics featuring some highlights from this table of contents:
1,600+ personalities in American gymnastics from 1880-date identified.
500+ line drawings to show how personalities looked during their prime years.
Covers show chronology of gymnastics from Rousseau to Hamm.
All original Hall of Fame honorees and most recent honorees are identified.
A comprehensive bibliography is included.
Table of contents identifies geographic relationships.
Name index leads the reader to specific individuals.
Grandfather of world gymnastics identified.
Modern father of gymnastics identified
American Grandfather and Father of gymnastics identified.
Mother figures for women’s artistic and rhythmic gymnastics identified.
American World Championship medalists and Olympic medalists identified.

You can order the entire book of his 3rd Ed. for $22 including S&H in the USA.