Differentiation in Freemium: Where Does the Line Lie? - Davide Semenzin; Edwin Meulendijks; Wilbert Seele; Christoph Wagner; Sjaak Brinkkemper (ICSOB, 2012)

The Functional Architecture Modeling Method Applied on Web Browsers. - Wilbert Seele; Shaheen Syed; Sjaak Brinkkemper (WICSA, 2014)