kaufman, J. (2013). The first 20 hours: How to learn anything fast. Portfolio Penguin.
Chicago-čujuhus (17. p.)kaufman, Josh. The First 20 Hours: How to Learn Anything Fast. London: Portfolio Penguin, 2013.
MLA-čujuhus (9. p.)kaufman, Josh. The First 20 Hours: How to Learn Anything Fast. Portfolio Penguin, 2013.
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