(en) Keirsey, David, Please Understand Me II : Temperament, Character, Intelligence, Del Mar, CA, Prometheus Nemesis Book Company, , 350 p. (ISBN978-1-885705-02-0, LCCN98218142), p. 205.
(en) Barron-Tieger, Barbara; Tieger, Paul D., Do what you are : discover the perfect career for you through the secrets of personality type, Boston, Little, Brown, , 2e éd., 350 p. (ISBN978-0-316-84522-9, OCLC32310807, LCCN95014317).
(en) Barron-Tieger, Barbara; Tieger, Paul D., Do what you are : discover the perfect career for you through the secrets of personality type, Boston, Little, Brown, , 2e éd., 350 p. (ISBN978-0-316-84522-9, OCLC32310807, LCCN95014317).