1
2
by Fage, J. D.
Published 1958
3
by Bever, Edward
Published 1996
4
by Gruhn, Isebill V.
Published 1979
5
Published 1996
6
7
Published 1992
8
Published 1967
9
by Cheru, Fantu
Published 1989
10
Published 1989
11
by Decalo, Samuel
Published 1990
12
Published 1983
13
Published 1986
14
by Morikawa, Jun
Published 1997
15
by Appiah, Anthony
Published 1992
16
Published 1992
17
Published 1987
18
by Schraeder, Peter J.
Published 1994
19
Published 1995
20
Published 1983