APA (7th ed.) Citation

Checkland, P. (1999). Soft systems methodology: A 30 year retrospective. John Wiley and Sons.

Chicago Style (17th ed.) Citation

Checkland, Peter. Soft Systems Methodology: A 30 Year Retrospective. Chichester: John Wiley and Sons, 1999.

MLA (9th ed.) Citation

Checkland, Peter. Soft Systems Methodology: A 30 Year Retrospective. John Wiley and Sons, 1999.