@article{AIHPA_1976__24_4_367_0,
     author = {Frehland, Eckart},
     title = {Convergence and accuracy of approximation methods in general relativity. {The} time-independent case},
     journal = {Annales de l'institut Henri Poincar\'e. Section A, Physique Th\'eorique},
     pages = {367--391},
     publisher = {Gauthier-Villars},
     volume = {24},
     number = {4},
     year = {1976},
     mrnumber = {426773},
     zbl = {0345.53014},
     language = {en},
     url = {http://www.numdam.org/item/AIHPA_1976__24_4_367_0/}
}