K. Sousa, H. Mendonça, and J. Vanderdonckt. Task Models and Diagrams for User Interface Design, volume 4849 of Lecture Notes in Computer Science, Springer Berlin Heidelberg, (2007)
K. Sousa, H. Mendonça, and J. Vanderdonckt. Task Models and Diagrams for User Interface Design, volume 5963 of Lecture Notes in Computer Science, Springer Berlin Heidelberg, (2010)