H. Kitapci, B. Boehm, P. Grünbacher, M. Halling, S. Biffl:
"Formalizing informal stakeholder requirements inputs";
in: "13th annual INCOSE Symposium, July 1-3, 2003 ", issued by: Int. Council on Systems Engineering; International Council on Systems Engineering, 2003, ISBN: 0-9720562-1-1, 447 - 459.