ABD-ELHAMEED, Waleed M. M. An elegant operational matrix based on harmonic numbers: Effective solutions for linear and nonlinear fourth-order two point boundary value problems. Nonlinear Analysis: Modelling and Control, [S. l.], v. 21, n. 4, p. 448–464, 2016. DOI: 10.15388/NA.2016.4.2. Disponível em: https://www.journals.vu.lt/nonlinear-analysis/article/view/13454.. Acesso em: 18 jul. 2024.