Melenk, J.M. and Babuška, I. (1997) “Approximation with harmonic and generalized harmonic polynomials in the partition of unity method”, Computer Assisted Methods in Engineering and Science, 4(3-4), pp. 607–632. Available at: https://cames.ippt.gov.pl/index.php/cames/article/view/1394 (Accessed: 5 March 2026).