1
2
3
by Slack, Nigel
Published 2004
4
by Abdullah Hassan
Published 1982
5
by Soars, Liz
Published 2000
6
7
by Gilbert, David
Published 2003
8
by Ulrich, Laurie
Published 2004
9
by Mankiw, N. Gregory
Published 2004
10
11
12
13
14
15
by Zill, Dennis G.
Published 2000
16
by Hoggett, John
Published 2009
17
by Hutchings, Glen
Published 2009
18
19
by Wood, Frank
Published 2008
20