A generic business model for WLAN hotspots: a roaming business case in The Netherlands. - Jack P. C. Verhoosel; Roel Stap; Alfons H. Salden (WMASH, 2003)

Contexts for Concepts: Information Modeling for Semantic Interoperability. - Paul Oude Luttighuis; Roel Stap; Dick A. C. Quartel (IWEI, 2011)