1. Entrance age to kindergarten and first grade: Its effects on cognitive and affective development of students;Beattie,1970
2. School progress of underage children;Bigelow;Elementary School Journal,1934
3. Developmentally appropriate practice in early childhood programs serving children ages birth through age eight;Bredekamp,1987
4. The California Achievement Test;CTB/McGraw Hill,1977
5. Cole's Cross Reference Directory: Pittsburgh-Allegheny County 1986–1987 issue,1986