@article{10_1017_S0017089500002780,
     author = {Popoola, J. O. and Tweddle, I.},
     title = {On the closed graph theorem},
     journal = {Glasgow mathematical journal},
     pages = {89--97},
     year = {1976},
     volume = {17},
     number = {2},
     doi = {10.1017/S0017089500002780},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500002780/}
}