@article{MM2_1996__90_2_156193,
     author = {Nobuhiko Ishida and Noburo Ishii},
     title = {The {Equations} for {Modular} {Function} {Fields} of {Principal} congruence subgroups of prime level.},
     journal = {Manuscripta mathematica},
     pages = {271--286},
     publisher = {mathdoc},
     volume = {90},
     number = {2},
     year = {1996},
     zbl = {0871.11031},
     url = {http://geodesic.mathdoc.fr/item/MM2_1996__90_2_156193/}
}