@article{GDZPPN002045990,
title = {Combinatorial principles concerning approximations of functions.},
journal = {Archiv f\"ur mathematische Logik und Grundlagenforschung},
volume = {26},
year = {1987},
pages = {13-28},
zbl = {0645.03057},
url = {http://dml.mathdoc.fr/item/GDZPPN002045990}
}
Hájek, Petr; Paris, Jeff. Combinatorial principles concerning approximations of functions.. Archiv für mathematische Logik und Grundlagenforschung, Tome 26 (1987) pp. 13-28. http://gdmltest.u-ga.fr/item/GDZPPN002045990/