A "matching" method for planar harmonic functions is exhibited, using an elliptic adjoint equation .
@article{BUMI_2009_9_2_1_239_0, author = {Orazio Arena}, title = {A Gluing Theorem for the Elliptic Adjoint Operator $L^{\star}$ in the Plane}, journal = {Bollettino dell'Unione Matematica Italiana}, volume = {2}, year = {2009}, pages = {239-244}, zbl = {1176.31001}, mrnumber = {2493653}, language = {en}, url = {http://dml.mathdoc.fr/item/BUMI_2009_9_2_1_239_0} }
Arena, Orazio. A Gluing Theorem for the Elliptic Adjoint Operator $L^{\star}$ in the Plane. Bollettino dell'Unione Matematica Italiana, Tome 2 (2009) pp. 239-244. http://gdmltest.u-ga.fr/item/BUMI_2009_9_2_1_239_0/
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