@article{01140261, title = {The Neumann problem for the 2-D Helmholtz equation in a domain, bounded by closed and open curves.}, journal = {International Journal of Mathematics and Mathematical Sciences}, volume = {21}, year = {1998}, pages = {209-216}, doi = {10.1155/S0161171298000301}, zbl = {0910.35040}, language = {en}, url = {http://dml.mathdoc.fr/item/01140261} }
Krutitskii, P.A. The Neumann problem for the 2-D Helmholtz equation in a domain, bounded by closed and open curves.. International Journal of Mathematics and Mathematical Sciences, Tome 21 (1998) pp. 209-216. doi : 10.1155/S0161171298000301. http://gdmltest.u-ga.fr/item/01140261/