Ackoff, Russell L. - Co-author of "Introduction to Operations Research", former Professor of Management Science at the Wharton Business School, University of Pennsylvania, author of the Management f-Laws and well known Systems Thinker.
Bhaskar, R. - Author of "A Realist Theory of Science", a non-mainstream philosopher and founder of [Critical Realism], and World Scholar at the London University Institutue of Education.
Churchman, C. West - Co-author of "Introduction to Operations Research", former Professor of Business Administration at the University of California at Berkeley and founder of the [US] Institute of Operations Research and Management Science
Midgely, G. - Author of a number of texts on Systems Thinking including Systems Thinking Vols. I - IV, Professor of Systems Thinking and Director, Centre for Systems Studies at the University of Hull.