@article{10_4064_am_16_4_621_629,
     author = {M. M. Sys{\l}o},
     title = {Generalizations of the standard travelling salesman problem},
     journal = {Applicationes Mathematicae},
     pages = {621--629},
     publisher = {mathdoc},
     volume = {16},
     number = {4},
     year = {1977},
     doi = {10.4064/am-16-4-621-629},
     zbl = {0463.90091},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/am-16-4-621-629/}
}