Alfred Horn. The separation theorem of intuitionist propositional calculus. The journal of symbolic logic, vol. 27 no. 4 (for 1962, pub. 1963), pp. 391–399.
1970 ◽
Vol 16
(8)
◽
pp. 469-474
◽
1966 ◽
Vol 42
(2)
◽
pp. 67-69
◽