TY  - BOOK
AU  - Esler, William K.
AU  - Esler, Mary K.
ED  - 
ED  - 
ED  - 
ED  - 
SN  - 534095283
SN  - 2
PY  - 1989///];copyright 1989.46
CY  - Belmont, Calif.
PB  - Wadsworth Pub. Co.
KW  - 
KW  - 2
KW  - 0
KW  - 6
KW  - 20
KW  - Study and teaching (Elementary)
KW  - Science
N1  - Includes bibliographies and index; 5
ER  -