21
Published 2004
22
by Watt, Montgomery
Published 1961
23
Published 1960
24
by Niazi, Kausar
Published 1974
25
by Akbar, B. A.
Published 1990
26
by Azzam, Abd-al-Rahman
Published 1964
27
by Tritton, A. S, 1881-1973
Published 1951
28
by Benda, Harry J.
Published 1958
29
by Bennigsen, Alexandre
Published 1967
30
31
32
by Grunebaum, G. E. Von.
Published 1961
33
by Watt, W. Montgomery
Published 1956