Rujukan

Mohd Salleh Lebar. 1994. Asas psikologi perkembangan.Utusan publications and distributors Sdn. Bhd.

Catherine Lee. The growth and development of children. Edisi ke-3. London. Longman.

Bentzen, W. R. Seeing young children: A guide to observing and recording behavior. Ed. ke-5. New York: state university.

Ma’rof & Haslinda Abdullah. 2004. Psikologi. Universiti Putra Malaysia.