%% -*-BibTeX-*- @Article{Groetschel1980a, author = "Martin Gr{\"o}tschel", title = "On the symmetric travelling salesman problem: solution of a 120-city problem", journal = "Mathematical Programming Study", volume = "12", publisher = "North-Holland", pages = "61--77", year = "1980", classmath = "*90C10 65K05 90C09", language = "English", }