@article{RO_1978__12_4_369_0,
     author = {d'Atri, Gianfranco},
     title = {Improved lower bounds to the travelling salesman problem},
     journal = {RAIRO - Operations Research - Recherche Op\'erationnelle},
     pages = {369--382},
     publisher = {EDP-Sciences},
     volume = {12},
     number = {4},
     year = {1978},
     mrnumber = {516515},
     zbl = {0399.90094},
     language = {en},
     url = {http://www.numdam.org/item/RO_1978__12_4_369_0/}
}