@article{1183532212, author = {Brooks, R.}, title = {The number of roots of $f\left( x \right) = a$}, journal = {Bull. Amer. Math. Soc.}, volume = {76}, number = {4}, year = {1970}, pages = { 1050-1052}, language = {en}, url = {http://dml.mathdoc.fr/item/1183532212} }
Brooks, R. The number of roots of $f\left( x \right) = a$. Bull. Amer. Math. Soc., Tome 76 (1970) no. 4, pp. 1050-1052. http://gdmltest.u-ga.fr/item/1183532212/