@article{NUMA_1989__54_3_133322,
     author = {Martin Costabel and Ernst P. Stephan},
     title = {Duality {Estimates} for the {Numerical} {Solution} of {Integral} {Equations.}},
     journal = {Numerische Mathematik},
     pages = {339--354},
     publisher = {mathdoc},
     volume = {54},
     number = {3},
     year = {1989},
     zbl = {0663.65141},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1989__54_3_133322/}
}