@article{1375834,
      recid = {1375834},
      author = {Siemon, Dianne, and Barkatsas, Anastasios, and Seah,  Rebecca,},
      title = {Researching and using progressions (trajectories) in  mathematics education /},
      pages = {1 online resource (255 pages).},
      url = {http://library.usi.edu/record/1375834},
}