Ulrich Langer G. Of Olaf Steinbach Walter Zulehner Inexact Data-Sparse Boundary Element Tearing and Interconnecting Methods. 290-314 2007 29 SIAM J. Scientific Computing 1 http://dx.doi.org/10.1137/050636243 db/journals/siamsc/siamsc29.html#LangerOSZ07