8.4.2 Optimal Solution for TSP using Branch and Bound
https://gtl.csa.iisc.ac.in/dsa/node187.html
Branch-and-bound algorithm for the traveling salesman problem
https://www.math.cmu.edu/~bkell/21257-2014f/tsp.pdf
Held–Karp algorithm - Wikipedia
https://en.wikipedia.org/wiki/Held%E2%80%93Karp_algorithm
Traveling Salesman Problem using Branch And Bound - GeeksforGeeks
https://www.geeksforgeeks.org/traveling-salesman-problem-using-branch-and-bound-2/
Travelling salesman problem - Wikipedia
https://en.wikipedia.org/wiki/Travelling_salesman_problem