21
by Brown
Published 1990
22
by Davis
Published 1985
23
by Wolf
Published 1986
24
by Spector
Published 1981
25
by Eliason
Published 1993
26
by Klecka
Published 1980
27
by Scrodt
Published 1987
28
29
by Cromwell
Published 1994
30
by Bailey
Published 1994
31
by Benfer
Published 1991
32
by Jacob
Published 1984
33
by Berry
Published 1984
34
by Zagare
Published 1984
35
by Mckewn
Published 1988
36
by Menard
Published 1991
37
by Hildebrand
Published 1977
38
by Levine
Published 1977
39
by Langbein
Published 1978
40
by Knoke
Published 1982