1
by Etzioni
Published 2004
2
3
by Obama
Published 2004
4
5
6
by Koenig
Published 1980
7
by Kessner
Published 1981
8
9
10
Published 2007
11
by Rothman
Published 2005
12
by Blum
Published 2007
13
by Berns
Published 2001
14
by Grant
Published 1979
15
by Stanley
Published 1988
16
by Harrington
Published 1977
17
by Bradshaw
Published 1972
18
19
20