This upper bound was first reported in:

J. Christopher Beck, T. K. Feng, Jean-Paul Watson. Combining Constraint Programming and Local Search for Job-Shop Scheduling. INFORMS Journal on Computing 23(1): 1-14 (2011).

The actual solution on this page was provided by CP Optimizer as described in:

Petr Vilím, Philippe Laborie and Paul Shaw. Failure-directed Search for Constraint-based Scheduling. In Proc. 12th International Conference on Integration of AI and OR Techniques in Constraint Programming for Combinatorial Optimization Problems (CPAIOR 2015). To appear.