@article{GDZPPN00210301X,
title = {Bounds on the number of non-rational subfields of a function field.},
journal = {Inventiones mathematicae},
volume = {83},
year = {1986},
pages = {185-198},
zbl = {0615.12017},
url = {http://dml.mathdoc.fr/item/GDZPPN00210301X}
}
Kani, E. Bounds on the number of non-rational subfields of a function field.. Inventiones mathematicae, Tome 83 (1986) pp. 185-198. http://gdmltest.u-ga.fr/item/GDZPPN00210301X/