German chemist Johann Wolfgang Döbereiner's observation of similarities among certain elements anticipated the development of the periodic system of elements.
Johann Wolfgang Döbereiner. (2013). The Biography Channel website. Retrieved 07:53, May 23, 2013, from http://www.biography.com/people/johann-wolfgang-döbereiner-9275855.
Johann Wolfgang Döbereiner. [Internet]. 2013. The Biography Channel website. Available from: http://www.biography.com/people/johann-wolfgang-döbereiner-9275855 [Accessed 23 May 2013].
"Johann Wolfgang Döbereiner." 2013. The Biography Channel website. May 23 2013, 07:53 http://www.biography.com/people/johann-wolfgang-döbereiner-9275855.
"Johann Wolfgang Döbereiner," The Biography Channel website, 2013, http://www.biography.com/people/johann-wolfgang-döbereiner-9275855 [accessed May 23, 2013].
"Johann Wolfgang Döbereiner," The Biography Channel website, http://www.biography.com/people/johann-wolfgang-döbereiner-9275855 (accessed May 23, 2013).
Johann Wolfgang Döbereiner [Internet]. The Biography Channel website; 2013 [cited 2013 May 23] Available from: http://www.biography.com/people/johann-wolfgang-döbereiner-9275855.
Johann Wolfgang Döbereiner, http://www.biography.com/people/johann-wolfgang-döbereiner-9275855 (last visited May 23, 2013).
Johann Wolfgang Döbereiner. The Biography Channel website. 2013. Available at: http://www.biography.com/people/johann-wolfgang-döbereiner-9275855. Accessed May 23, 2013.