Scottish marine engineer John Elder developed the marine compound steam engine, which enabled seagoing vessels to save coal and delay refueling.
John Elder. (2013). The Biography Channel website. Retrieved 05:02, Jun 18, 2013, from http://www.biography.com/people/john-elder-38627.
John Elder. [Internet]. 2013. The Biography Channel website. Available from: http://www.biography.com/people/john-elder-38627 [Accessed 18 Jun 2013].
"John Elder." 2013. The Biography Channel website. Jun 18 2013, 05:02 http://www.biography.com/people/john-elder-38627.
"John Elder," The Biography Channel website, 2013, http://www.biography.com/people/john-elder-38627 [accessed Jun 18, 2013].
"John Elder," The Biography Channel website, http://www.biography.com/people/john-elder-38627 (accessed Jun 18, 2013).
John Elder [Internet]. The Biography Channel website; 2013 [cited 2013 Jun 18] Available from: http://www.biography.com/people/john-elder-38627.
John Elder, http://www.biography.com/people/john-elder-38627 (last visited Jun 18, 2013).
John Elder. The Biography Channel website. 2013. Available at: http://www.biography.com/people/john-elder-38627. Accessed Jun 18, 2013.