@incollection {121607, title = {Alternative mathematics: the vague way.}, booktitle = {Festschrift in honor of {N}ewton {C}.{A}. da {C}osta on the occasion of his seventieth birthday}, volume = {125}, year = {2000}, pages = {19{\textendash}31}, publisher = {Kluwer Academic}, isbn = {N/A}, author = {Van Bendegem, Jean Paul}, editor = {Krause, D{\'e}cio and French, Steven and Doria, Francisco A.} }