Analysis of information sources in references of the Wikipedia article "William Playfair" in English language version.
William Playfair, for example, is often credited with inventing the bar chart (see Chapter 3) in the last part of the 18th century, although a Frenchman, Nicole Oresme, used a bar chart in a 14th century publication, The Latitude of Forms to plot the velocity of a constantly accelerating object against time. But it was Playfair who popularized the idea of graphic depiction of quantitative information.
