Diab, S.
(2023).
 The natural boundary conditions as a variational basis for finite element methods.
<em>Computer Assisted Methods In Engineering And Science, 8</em>(2-3), 213-226.
Retrieved from <a href="https://cames.ippt.gov.pl/index.php/cames/article/view/1165" target="_new">https://cames.ippt.gov.pl/index.php/cames/article/view/1165</a>