21
by Spera
Published 1997
22
by Heil
Published 1993
23
by Willis
Published 1992
24
by Marcus
Published 2003
25
by Maxwell
Published 2011
26
by Henman
Published 2011
27
by Kubicek
Published 2011
28
29
30
by Rejeski
Published 1988
31
by Gavin
Published 1992
32
by Hunt
Published 1996
33
by Nash
Published 1982
34
by Rejeski
Published 1989
35
by Biddle
Published 2001
36
37
Published 1995
38