@article{oai:tsukuba.repo.nii.ac.jp:00017249, author = {Costantini, Camillo and Gutev, Valentin}, issue = {1}, journal = {Tsukuba Journal of Mathematics}, month = {Jun}, pages = {145--169}, title = {Recognizing special metrics by topological properties of the “metric”-proximal hyperspace}, volume = {26}, year = {2002} }