Jiaxuan Zhang Suogang Gao Bo Hou Wen Liu 0009 An approximation algorithm for the clustered path travelling salesman problem. 104 2023 May 45 J. Comb. Optim. 4 https://doi.org/10.1007/s10878-023-01029-2 db/journals/jco/jco45.html#ZhangGHL23