by Lowe, G.S, Hartnagel, T.F, Krahn, H, Tanner, J
Published in International journal of comparative sociology (1987)

by Hartnagel, T.F, Krahn, H
Published in Youth & society (01.06.1989)

by Krahn, H., Lowe, G.S., Hartnagel, T.F., Tanner, J.
Published in International journal of comparative sociology (01.09.1987)