@Article{ MOLINA_AMBROSE:61-80,
author = { MARTA MOLINA and REBECCA AMBROSE } ,
title = { FROM AN OPERATIONAL TO A RELATIONAL CONCEPTION OF THE EQUAL SIGN. THIRDS GRADERS¿ DEVELOPING ALGEBRAIC THINKING. },
journal = { FOCUS ON LEARNING PROBLEMS IN MATHEMATICS },
year = { 2008 },
volume = { 30 },
issn = { 0272-8893 },
pages = { 61-80 },
}