Patterson, A.M. "An Introduction to Chemistry." Journal of the American Chemical Society, vol. 25, no. 3, 1903, p. 317.
"Physical and Chemical Properties." NDT Education Resource Center, www.nde-ed.org/EducationResources/CommunityCollege/Materials/Physical_Chemical/PhysicalProperties.htm. Accessed 3 July 2018.
"What is a Plasma?" The University of Manchester, people.man.ac.uk/~mbdsszjw/Pages/WhatisaPlasma.php. Accessed 3 July 2018.