@INPROCEEDINGS {10654,
author={F. Martins},
doi={},
booktitle={Conf. of the International Group for the Psychology of Mathematics Education},
title={Early Years’ Trainee Teachers Mathematical Knowledge for Teaching: The Case of Bar Graphs (F. Martins e C. Miguel Ribeiro)},
year={2011},
month={July},
volume={1},
pages={491-491} 
}