@misc {IOPORT.70579932,
    author       = {Bekker, Tilde and Sturm, Janienke},
    title        = {Stimulating physical and social activity through open-ended play},
    howpublished = {IDC, 309-312 (2009).},
    year         = {2009},
    doi          = {10.1145/1551788.1551869},
    identifier   = {70579932},
}