Some inequalities for the Hersch-Pfluger distortion function. Qiu, S.-L.; Vamanamurthy, M.K.; Vuorinen, M. — 1999 Journal of Inequalities and Applications [electronic only]
Submultiplicative properties of the φ K -distortion function S.-L. Qiu; M. Vuorinen — 1996 Studia Mathematica Some inequalities related to the submultiplicative properties of the distortion function φ K ( r ) are derived.