Johnson, D. W., & Johnson, F. P. (1975). Joining together: Group theory and group skills. Prentice-Hall.

Johnson, David W., and Frank P. Johnson. Joining Together: Group Theory and Group Skills. Englewood Cliffs, N.J.: Prentice-Hall, 1975.

Johnson, David W., and Frank P. Johnson. Joining Together: Group Theory and Group Skills. Prentice-Hall, 1975.