1. O-regularly varying functions;Aljančić;Publ. Inst. Math. (N.S.),1977
2. Regular Variation;Bingham,1987
3. On Slowly Varying Functions and Asymptotic Relations;Bojanić,1963
4. The cosine series and regular variation in the Karamata and Zygmund senses;Bojanić;Publ. Inst. Math. (N.S.),2018
5. On the order of functions at infinity;Cadena;J. Math. Anal. Appl.,2017