  We extend the results of Xh. Z. Krasniqi [Acta Comment. Univ. Tartu. Math. 17
(2013), 89-101] and the authors [Acta Comment. Univ. Tartu. Math. 13 (2009),
11-24]. to the case where in the measures of estimations there are used
$r$-differences of the entries.
