by Young, C.Y., Georgiopoulos, M., Hagen, S.C., Geiger, C.L., Dagley-Falls, M.A., Islas, A.L., Ramsey, P.J., Lancey, P.M., Straney, R.A., Forde, D.S., Bradbury, E.E.
Published in International journal of mathematical education in science and technology (15.07.2011)