Wolff, J. Focus: Use the power of targeted thinking to get more done : Use the power of targeted thinking to get more done (2.). Pearson Education UK.
Chicago-viite (17. p.)Wolff, Jurgen. Focus: Use the Power of Targeted Thinking to Get More Done : Use the Power of Targeted Thinking to Get More Done. 2. Pearson Education UK.
MLA-viite (8. p.)Wolff, Jurgen. Focus: Use the Power of Targeted Thinking to Get More Done : Use the Power of Targeted Thinking to Get More Done. 2. Pearson Education UK.
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