Satisfying heterogeneous user needs via innovation toolkits: the case of Apache security software. Research Policy. 2003;32:1199-1215. rp-vonhippelfranke.pdf (462.28 KB) .
How open source software works: "free" user-to-user assistance. Research Policy [Internet]. 2003;32:923-943. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.110.8172&rep=rep1&type=pdf lakhani2003.pdf (248.56 KB) .