@article{10_4153_CJM_1981_021_x,
     author = {Furuta, Takayuki},
     title = {Essentially {Convexoid} {Operators}},
     journal = {Canadian journal of mathematics},
     pages = {257--274},
     year = {1981},
     volume = {33},
     number = {2},
     doi = {10.4153/CJM-1981-021-x},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1981-021-x/}
}