𝒪 -regularly varying functions in approximation theory. Jansche, Stefan (1997) Journal of Inequalities and Applications [electronic only]
0-regularity varying function. S. Aljancic, D. Arandjelovic (1977) Publications de l'Institut Mathématique [Elektronische Ressource]
λ-Regular Oscillation And Applications Bogdan Baishanski, Ranko Bojanić (1990) Publications de l'Institut Mathématique