Xavier Delorme Joaquin Rodriguez Xavier Gandibleux Heuristics for railway infrastructure saturation. 2001 50 Electr. Notes Theor. Comput. Sci. 1 http://www.elsevier.com/gej-ng/31/29/23/85/27/show/Products/notes/index.htt#006 db/journals/entcs/entcs50.html#DelormeRG01