Herbert Hoover has telephone installed in Oval Office. (2013). The History Channel website. Retrieved 11:41, May 18, 2013, from http://www.history.com/this-day-in-history/herbert-hoover-has-telephone-installed-in-oval-office.
Herbert Hoover has telephone installed in Oval Office. [Internet]. 2013. The History Channel website. Available from: http://www.history.com/this-day-in-history/herbert-hoover-has-telephone-installed-in-oval-office [Accessed 18 May 2013].
“Herbert Hoover has telephone installed in Oval Office.” 2013. The History Channel website. May 18 2013, 11:41 http://www.history.com/this-day-in-history/herbert-hoover-has-telephone-installed-in-oval-office.
“Herbert Hoover has telephone installed in Oval Office,” The History Channel website, 2013, http://www.history.com/this-day-in-history/herbert-hoover-has-telephone-installed-in-oval-office [accessed May 18, 2013].
“Herbert Hoover has telephone installed in Oval Office,” The History Channel website, http://www.history.com/this-day-in-history/herbert-hoover-has-telephone-installed-in-oval-office (accessed May 18, 2013).
Herbert Hoover has telephone installed in Oval Office [Internet]. The History Channel website; 2013 [cited 2013 May 18] Available from: http://www.history.com/this-day-in-history/herbert-hoover-has-telephone-installed-in-oval-office.
Herbert Hoover has telephone installed in Oval Office, http://www.history.com/this-day-in-history/herbert-hoover-has-telephone-installed-in-oval-office (last visited May 18, 2013).
Herbert Hoover has telephone installed in Oval Office. The History Channel website. 2013. Available at: http://www.history.com/this-day-in-history/herbert-hoover-has-telephone-installed-in-oval-office. Accessed May 18, 2013.