@article{AFM_1986_11_2_a6,
     author = {K. F. Barth and D. A. Brannan},
     title = {Asymptotic tracts of harmonic functions {I}},
     journal = {Annales Fennici Mathematici},
     pages = {215--232},
     publisher = {mathdoc},
     volume = {11},
     number = {2},
     year = {1986},
     doi = {10.5186/aasfm.1986.1102},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.5186/aasfm.1986.1102/}
}