@article{TM2_2006_IX_1_a4,
     author = {Levent Akg\"un and M. Emin \"Ozdemir},
     title = {Students' understanding of the variable as general number and unknown: a case study},
     journal = {The Teaching of Mathematics},
     pages = {45 },
     publisher = {mathdoc},
     volume = {IX},
     number = {1},
     year = {2006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TM2_2006_IX_1_a4/}
}