}, B., J., {., E., A.(2013).Thinking Skills Critical Thinking and Problem Solving .Cambridge,:c a m b r i d g e u n i v e r s i t y p r e s s.
Gaya MLA
Butterworth, John, {, Et, Al, }."Thinking Skills Critical Thinking and Problem Solving".Cambridge,:c a m b r i d g e u n i v e r s i t y p r e s s,2013.Buku Pelajaran.