Table 2.

Frequency of the most important green criteria.

	Govindan et al.	Nielsen et al.
Duration	1996–2011	1996–2014
Number of reviewed papers	33	57
Criterion
Environmental management system	11	20
Green image	4	8
Environmental competences	3	6
Design for environment	3	5
Environmental improvement costs	2	5
Environmental performance	3	5