@article{10_1017_S001708950103004X,
     author = {Ko, Eungil},
     title = {On {hypo-Jordan} operators},
     journal = {Glasgow mathematical journal},
     pages = {411--418},
     year = {2001},
     volume = {43},
     number = {3},
     doi = {10.1017/S001708950103004X},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S001708950103004X/}
}