Lawn, Philip A. (2003). "A theoretical foundation to support the Index of Sustainable Economic Welfare (ISEW), Genuine Progress Indicator (GPI), and other related indexes". Ecological Economics. 44 (1): 105–118. Bibcode:2003EcoEc..44..105L. doi:10.1016/S0921-8009(02)00258-6.
Lawn, Philip A. (2003). "A theoretical foundation to support the Index of Sustainable Economic Welfare (ISEW), Genuine Progress Indicator (GPI), and other related indexes". Ecological Economics. 44 (1): 105–118. Bibcode:2003EcoEc..44..105L. doi:10.1016/S0921-8009(02)00258-6.