 More evidence comes from Walker and Richards' s finding that moral development to Kohlberg's stage 4 occurred only for those who already had early basic formal operations according to Piaget's developmental theory, and not for those in an earlier stage.
<meaning-changed>  More evidence comes from Walker and Richards' s finding that moral development to Kohlberg's stage 4 occurred only for those who already had early basic formal operations according to Piaget's developmental theory, and not for those in an earlier stage.
 More evidence comes from Walker and Richards' (1979) finding that moral development to Kohlberg's stage 4 occurred only for those who already had early basic formal operations according to Piaget's developmental theory, and not for those in an earlier stage.