"Max Planck." Encyclopaedia Britannica. Encyclopaedia Britannica Online Academic Edition. Encyclopædia Britannica Inc., 2015. Web. 14 May. 2015. <http://academic.eb.com.ezp-prod1.hul.harvard.edu/EBchecked/topic/462888/Max-Planck>.
MLA style: "Max Planck - Facts". Nobelprize.org. Nobel Media AB 2014. Web. 13 May 2015. <http://www.nobelprize.org/nobel_prizes/physics/laureates/1918/planck-facts.html>