However , Calvin himself does not appear in either book .
Similarly , Dr. Austin mentions O'Keefe to Canon Tallis in the previous Austin book , The Young Unicorns ( 1968 , ISBN 0 - 374 - 38778 - 8 ) .
O'Keefe himself does not appear in either book .
Similarly , Dr. Austin mentions O'Keefe to Canon Tallis in the previous Austin book , The Young Unicorns ( 1968 , ISBN 0 - 374 - 38778 - 8 ) .