Citing a telegram using the Modern Languages Association or American Psychological Association format requires you treat it as a primary source document and must include information such as the sender, addressee and date. You should also include available identification of the telegram's present location, such the name of an archive or library collection and, in the case of an APA citation, the specific folder or box in which the telegram is stored.
Following the MLA citation format, list the telegram author, followed by the date the telegram was sent and the collection that contains the telegram. Telegrams that have been digitized can also include a Web link to the document. An example, using the Morse telegram: Morse, Samuel. 24 May 1844. The Samuel Finley Breese Morse Papers at the Library of Congress, 1793-1919, Washington, D.C. http://hdl.loc.gov.mss/mmorse.071009
APA Telegram Citation
The APA citation of a telegram is very similar to the MLA method; however, the location of the telegram must be more specific, identifying the folder or folio in which the telegram is preserved. For example: Morse, S. (1844, May 24). The Samuel Finely Breese Morse Papers, 1793-1919 ((box 71, Folder 009), Library of Congress, Washington, D.C. http://hdl.loc.gov.mss/mmorse.071009