Bringing New Products to Market Speedily. Product & Process Innovation, 1(4): 5-10—- Ashok K. Gupta, David L. Wilemon, and Arvind Singhal (1991) —- http://utminers.utep.edu/asinghal/Articles%20and%20Chapters/Bringing%20New%20Products%20to%20Market%20Speedily%20(1991).pdf