@article{1183527952,
author = {Feferman, S. and Kreisel, G.},
title = {Persistent and invariant formulas relative to theories of higher order},
journal = {Bull. Amer. Math. Soc.},
volume = {72},
number = {4},
year = {1966},
pages = { 480-485},
language = {en},
url = {http://dml.mathdoc.fr/item/1183527952}
}
Feferman, S.; Kreisel, G. Persistent and invariant formulas relative to theories of higher order. Bull. Amer. Math. Soc., Tome 72 (1966) no. 4, pp. 480-485. http://gdmltest.u-ga.fr/item/1183527952/