Yamaguchi, S., and M. A. B. Ahmadon. “Process Tree-Based Analysis Method of DECLARE Relation Constraints in Acyclic Bridge-Less Well-Structured Workflow Nets”. ECTI Transactions on Computer and Information Technology (ECTI-CIT), vol. 13, no. 2, Oct. 2019, pp. 104-11, doi:10.37936/ecti-cit.2019132.203107.