1References addressing the scope & substance of Enterprise Systems as a discipline:
Wikipedia: Enterprise Engineering
Wikipedia: Enterprise Systems Engineering
Wikipedia: Business Engineering
Post, J. E., Preston, L. E., & Sachs, S. 2002. Managing the Extended Enterprise. California Management Review, 45(1): 6-28.
Valerdi, R., Nightingale, D., & Blackburn, C. 2008. Enterprises as systems: Context, boundaries, and practical implications. Information, Knowledge, Systems Management, 7(4): 377-399.
Rebovich Jr, G. 2006. Systems Thinking for the Enterprise: New and Emerging Perspectives. The MITRE Corporation.
Nightingale, D. (2009). Principles of Enterprise Systems, Second International Symposium on Engineering Systems. MIT, Cambridge, Massachusetts, June 15-17, 2009: MIT ESD and CESUN.
Nightingale, D., & Rhodes, D. (2004). Enterprise systems architecting: Emerging art and science within engineering systems. Fairbairn, A., & Farncombe, A. (2000).
Fairbairn, A., & Farncombe, A. 2000. Enterprise Systemics: Systems Thinking for plotting Strategy at the Extended Enterprise level. Paper presented at the 2nd European Systems Engineering Conference, Munich.