@article{CSIS_2006_3_1_a1,
     author = {Stellan Ohlsson and Antonija Mitrovic},
     title = {Constraint-Based {Knowledge} {Representation} for {Individualized} {Instruction}},
     journal = {Computer Science and Information Systems},
     publisher = {mathdoc},
     volume = {3},
     number = {1},
     year = {2006},
     url = {http://geodesic.mathdoc.fr/item/CSIS_2006_3_1_a1/}
}