Zacharos, K., M. Kilia, and K. Ravanis. “Familiarizing Pupils 4-6 Years Old With Forms of Spatial Representation. The Use of Photography As an Auxiliary Tool”. JOURNAL OF SOCIAL SCIENCE RESEARCH, vol. 4, no. 1, May 2014, pp. 454-63, doi:10.24297/jssr.v4i1.3233.