@incollection{Bal1:99, author = {V. Balakrishnan}, title = {Conditions for the existence and uniqueness of optimal matrix scalings}, booktitle = {Open Problems in Mathematical Systems and Control Theory}, chapter = {6}, year = {1999}, editor = {V. D. Blondel and E. D. Sontag and M. Vidyasagar and J. C. Willems}, publisher = {Springer Verlag}, address = {London} }