HIPPEL E V. Lead users:a source of novel product concepts[J]. Management Science,1986,32(7):791-805.
[2]
GURGUL G, RUMYANTSEVA M, ENKEL E. Customer i-ntegration-establish a constant bilateral knowledge flow[EB/OL]. [2010-06-13]. http://sm.bwa.unisg.ch/org/ifb/ifbweb.nsf/SysWebRessources/beitrag47/$FILE/DB47.pdf.