7 1 50 Primary 3 Additional Author Alter, J.B. Additional Author mixed material Jakarta Binarupa Aksara 1991 Additional Author Alter, J.B. Additional Author mixed material Hongkong Times Educational Co LTD 1979 Additional Author Alter, J.B. Additional Author mixed material Hongkong Times Educational Co LTD 1979 Additional Author Alter, J.B. Additional Author mixed material Hongkong Times Educational Co LTD 1979 Primary 2 Additional Author Alter, J.B. Additional Author mixed material Jakarta Binarupa Aksara 1991 Additional Author Alter, J.B. Additional Author mixed material Hongkong Times Educational 1981 Primary 1 Additional Author Alter, J.B. Additional Author mixed material Jakarta Bina Rupa Aksara 1991