Gaisi Takeuti and Mariko Yasugi. The ordinals of the systems of second order arithmetic with the provably -comprehension axiom and with the -comprehension axiom respectively. Japanese journal of mathematics, vol. 41 (1973), pp. 1–67.
Kurt Schütte · Journal of Symbolic Logic · 1983
Gaisi Takeuti and Mariko Yasugi. The ordinals of the systems of second order arithmetic with the provably -comprehension axiom and with the -comprehension axiom respectively. Japanese journal of mathematics, vol. 41 (1973), pp. 1–67. - Volume 48 Issue 3