Lal, S. and Nigam, H.K. 2001. Degree of approximation by $ (N, p, q) $ summability means of the Fourier-Laguerre expansion. Tamkang Journal of Mathematics. 32, 2 (Jun. 2001), 143–150. DOI:https://doi.org/10.5556/j.tkjm.32.2001.357.