Most are published under the Pelican Label and are not expensive
The Use of Lateral Thinking ( 1967 )
The Five-Day Course in Thinking ( 1968 )
The Mechanism of the Mind ( 1969 )
The Dog-Exercising Machine ( 170 )
Technology Today ( 1971 )
Lateral Thinking for management ( 1971 )
Po: Beyond Yes and No ( 1972 )
Children Solve Problems ( 1972 )
Eureka! An Illustrated History of Inventions from the Wheel to the Computer ( 1974 )
Teaching Thinking ( 1976 )
The Greatest Thinkers ( 1976 )
Practical Thinking ( 1976 )
Wordpower ( 1977 )
The Happiness Purpose ( 1977 )
Opportunities: A Handbook of Business Opportunity Search ( 1978 )
Future Positive ( 19779 )
Atlas of Management Thinking ( 1981 )
De Bono's Course in Thinking ( 1982 )
Tatics: The Art and Science of Success ( 1985 )
Conflicts: A better way to Resolve Them, and Six Thinking Hats