Mikhail A. Lyalinov, “Eigenmodes in the water-wave problems for infinite pools with cone-shaped bottom”, J. Fluid Mech., 800, 2016, 645
V.M. Babich, K.D. Cherednichenko, “On a differential equation with a singular point of regular type and a large parameter”, Integral Transforms and Special Functions, 11, № 2, 2001, 101
V. M. Babich, D. B. Dement’ev, B. A. Samokish, “Computation of Legendre functions”, J Math Sci, 148, № 5, 2008, 639