Neil A. M. Maiden Cornelius Ncube James Lockerbie Inventing Requirements: Experiences with an Airport Operations System. 58-72 2008 REFSQ http://dx.doi.org/10.1007/978-3-540-69062-7_6 conf/refsq/2008 db/conf/refsq/refsq2008.html#MaidenNL08