1
2
by Einstein
Published 2008
3
by Payne
Published 1993
4
by Gao
Published 1991
5
by Kotler
Published 1990
6
7
by Lovelock
Published 1990
8
Published 1992
9
by Peter
Published 1992
10
by McKenna
Published 1991
11
by Levinson
Published 1993
12
by Bartos
Published 1989
13
14
by Laaksonen
Published 1994
15
by Farbey
Published 1994
16
17
by Scher
Published 1992
18
19
by Chaston
Published 2004
20