@article{RSMUP_1986__75__257_0,
     author = {Alexandru, Victor and Popescu, Nicolae},
     title = {On subfields of $k(x)$},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
     pages = {257--273},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {75},
     year = {1986},
     mrnumber = {847671},
     zbl = {0596.12027},
     language = {en},
     url = {http://www.numdam.org/item/RSMUP_1986__75__257_0/}
}