Brown, Theodore L.; LeMay, H. Eugene; Bursten, Bruce E.; Murphy, Catherine J.; Woodward, Patrick (2013), Chemistry: The Central Science (3rd ed.), Frenchs Forest, NSW: Pearson/Prentice Hall, pp. 5–6, ISBN9781442559462, archived from the original on 2021-05-31, retrieved 2020-12-08
Hill, John W.; Petrucci, Ralph H.; McCreary, Terry W.; Perry, Scott S. (2005), General Chemistry (4th ed.), Upper Saddle River, NJ: Pearson/Prentice Hall, p. 6, ISBN978-0-13-140283-6, archived from the original on 2009-03-22
Brown, Theodore L.; LeMay, H. Eugene; Bursten, Bruce E.; Murphy, Catherine J.; Woodward, Patrick (2013), Chemistry: The Central Science (3rd ed.), Frenchs Forest, NSW: Pearson/Prentice Hall, pp. 5–6, ISBN9781442559462, archived from the original on 2021-05-31, retrieved 2020-12-08
Hill, John W.; Petrucci, Ralph H.; McCreary, Terry W.; Perry, Scott S. (2005), General Chemistry (4th ed.), Upper Saddle River, NJ: Pearson/Prentice Hall, p. 6, ISBN978-0-13-140283-6, archived from the original on 2009-03-22