| Title | Journal | Journal Categories | Citations | Publication Date |
|---|---|---|---|---|
| On Children's Quantitative Understanding of Numbers | 1975 | |||
| How Children Learn Mathematics | 1974 | |||
| Zahlbegriffsentwicklung und Erstrechenunterricht | 1973 | |||
| Mathematics as an Educational Task | 1973 | |||
| The understanding of invariance by very young children. | Canadian Journal of Psychology / Revue canadienne de psychologie | 30 | 1972 |