@article {HBI99, title = {On a Merging Reduction of the Process Network Synthesis Problem}, journal = {Acta Cybernetica}, volume = {14}, year = {1999}, pages = {251-261}, author = {Cs. Holl{\'o} and Z. Bl{\'a}zsik and Cs. Imreh and Z. Kov{\'a}cs} }