Soft Systems Methodology (glossary)
Soft Systems Methodology (SSM) formalizes the ideas of a soft system approach using systemic thinking to expose the issues in a problem situation and guide interventions to reduce them. SSM provides a framework of ideas and models to help guide participants through this systemic thinking.
Checkland, P. 1999. Systems Thinking, Systems Practice, New York, John Wiley & Sons.
SSM is the most common example for a Problem Structuring Approach, see Overview of System Science for details.