ZIENIUK, Eugeniusz, and Krzysztof SZERSZEŃ. 2009. “Triangular Bezier Patches in Modelling Smooth Boundary Surface in Exterior Helmholtz Problems Solved by the PIES”. Archives of Acoustics 34 (1): 51–61. https://acoustics3.ippt.pan.pl/index.php/aa/article/view/566.