Jennifer Lipton

Abstract number and arithmetic in preschool children.

Hilary Barth, Elizabeth S Spelke, E. Spelke, 2005, Proceedings of the National Academy of Sciences of the United States of America.

Nonsymbolic Arithmetic in Adults and Young Children

Nancy Kanwisher, Stanislas Dehaene, Hilary Barth, 2003 .

Non-symbolic arithmetic in adults and young children

Nancy Kanwisher, Stanislas Dehaene, Hilary Barth, 2006, Cognition.