This paper is about the use of systems thinking and systems theory in EA
https://www.linkedin.com/pulse/why-usm-systems-thinking-outperform-traditional-itsm-john-worthington-egxee/?trackingId=n8ekmPMH46PnB90K%2B3X1rg%3D%3D
How USM Uses the Viable System Model
Similarities and differnces between USM and GERAM