Transfinite Induction and Bar Induction of Types Zero and One, and the Role of Continuity in Intuitionistic Analysis. - William A. Howard; Georg Kreisel (J. Symb. Log., 1966)

A System of Abstract Constructive Ordinals. - William A. Howard (J. Symb. Log., 1972)

Ordinal Analysis of Terms of Finite Type. - William A. Howard (J. Symb. Log., 1980)

Ordinal Analysis of Simple Cases of Bar Recursion. - William A. Howard (J. Symb. Log., 1981)

Peirce's influence on today's mathematical logic. - William A. Howard (Cybern. Hum. Knowing, 2001)