Mott-Smith, Morton (1964) [Unabridged and revised version of the book first published by D. Appleton-Century Company in 1934 under the former title: The Story of Energy]. The Concept of Energy Simply Explained. New York: Dover Publications, Inc. стр. 13–14. ISBN978-0-486-21071-1.
Robert Lucas, Jr (2003). „The Industrial Revolution”. Federal Reserve Bank of Minneapolis. Архивирано из оригинала 16. 05. 2008. г. Приступљено 14. 11. 2007. „it is fairly clear that up to 1800 or maybe 1750, no society had experienced sustained growth in per capita income. (Eighteenth century population growth also averaged one-third of 1 percent, the same as production growth.) That is, up to about two centuries ago, per capita incomes in all societies were stagnated at around $400 to $800 per year.”
Lucas, Robert (2003). „The Industrial Revolution Past and Future”. Архивирано из оригинала 16. 5. 2008. г. Приступљено 3. 4. 2017. „[consider] annual growth rates of 2.4 percent for the first 60 years of the 20th century, of 1 percent for the entire 19th century, of one-third of 1 percent for the 18th century”
Robert Lucas, Jr (2003). „The Industrial Revolution”. Federal Reserve Bank of Minneapolis. Архивирано из оригинала 16. 05. 2008. г. Приступљено 14. 11. 2007. „it is fairly clear that up to 1800 or maybe 1750, no society had experienced sustained growth in per capita income. (Eighteenth century population growth also averaged one-third of 1 percent, the same as production growth.) That is, up to about two centuries ago, per capita incomes in all societies were stagnated at around $400 to $800 per year.”
Lucas, Robert (2003). „The Industrial Revolution Past and Future”. Архивирано из оригинала 16. 5. 2008. г. Приступљено 3. 4. 2017. „[consider] annual growth rates of 2.4 percent for the first 60 years of the 20th century, of 1 percent for the entire 19th century, of one-third of 1 percent for the 18th century”
