@article{DA_2009_16_4_a0,
     author = {A. A. Ageev and A. V. Pyatkin},
     title = {A 2-approximation algorithm for the metric 2-peripatetic salesman problem},
     journal = {Diskretnyj analiz i issledovanie operacij},
     pages = {3--20},
     publisher = {mathdoc},
     volume = {16},
     number = {4},
     year = {2009},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DA_2009_16_4_a0/}
}