Correction

Abstract

Biometrica (1966) 53, 497–506 p. 500 The seventh design should be (AE EA BC CB) (CE EC BH HB) not (AE EA BC CB) (CE ED BH HB) p. 503 The sixth design should be (AA DJ FP OB HE KN LQ MO OI) (AA BD CO EM IH JK NF PL QO) not (AA DJ FP OB HE KM LQ MC OI) (AA BD CO EM IF JK NF PL QO)