Nicos Christofides, Worst-case analysis of a new heuristic for the travelling salesman problem, Report 388, Graduate School of Industrial Administration, CMU, 1976.
Định nghĩa thuật toán Christofides ở NIST(tiếng Anh) Nicos Christofides, Worst-case analysis of a new heuristic for the travelling salesman problem, Báo cáo 388, Graduate School of Industrial Administration, CMU, 1976.(tiếng Anh)