TY  - BOOK
AU  - Checkland, Peter
TI  - Soft system methodology: a 30 year retrospective, systems thinking, system practice 
SN  - 9780471986065
U1  - 003 CHE 1999 
PY  - 1999///
CY  - Chichester
PB  - John Wiley
KW  - System theory
ER  -