1. U. Abel, M. Ivan, Some identities for the operator of Bleimann, Butzer and Hahn involving divided differences. Calcolo 36, 143–160 (1999)
2. O. Agratini, Approximation properties of a generalization of Bleimann, Butzer and Hahn operators. Math. Pannon. 9, 165–171 (1988)
3. O. Agratini, A class of Bleimann, Butzer and Hahn type operators. An. Univ. Timişoara Ser. Math. Inform. 34, 173–180 (1996)
4. O. Agratini, Note on a class of operators on infinite interval. Demons. Math. 32, 789–794 (1999)
5. O. Agratini, G. Nowak, On a generalization of Bleimann, Butzer and Hahn operators based on q-integers. Math. Comput. Model. 53(5–6), 699–706 (2011)