1
by Maddux, Robert B.
Published 1986
...The fifty-minute series...
2
by Maddux, Dorothy J.
Published 1989
...The fifty-minute series...
3
by Voorhess, Lynda A.
Published 1987
...Fifty-minute series...
4
by Maddux, Robert B.
Published 1990
...Fifty-Minute series....
5
by Maddux, Robert B.
Published 1988
...The Fifty-Minute series...
6
by Conrad, Pamela J.
Published 1988
...A fifty-minute series book...