United States. Army. Corps of Engineers & ProQuest (Firm). (1844). Magnetic observatory, at the Girard College, Philadelphia, ordinary magnetic and triple observations, from June to December, 1840. [publisher not identified].
Chicago Style (17th ed.) CitationUnited States. Army. Corps of Engineers and ProQuest (Firm). Magnetic Observatory, at the Girard College, Philadelphia, Ordinary Magnetic and Triple Observations, from June to December, 1840. Washington: [publisher not identified], 1844.
MLA (9th ed.) CitationUnited States. Army. Corps of Engineers and ProQuest (Firm). Magnetic Observatory, at the Girard College, Philadelphia, Ordinary Magnetic and Triple Observations, from June to December, 1840. [publisher not identified], 1844.
Warning: These citations may not always be 100% accurate.