Sharma, J. N. Singh, Kehar creator text New Delhi Narosa Publishing House 2019 monographic xiv, 339 p. : ill. ; 24 cm. Includes bibliography, appendix and index. Partial differential equations Mathematics Differential equations partial Differential equations Fourier series Differential equations, Elliptic Differential equations, Hyperbolic Functions FBSH 515.353 SHA 9788173198298 (pbk)