Gilbert Held Extend the product cycle. 67 1999 9 Int. J. Netw. Manag. 2 https://doi.org/10.1002/%28SICI%291099-1190%28199903/04%299:2%3C67::AID-NEM322%3E3.0.CO;2-2 db/journals/ijnm/ijnm9.html#Held99a