AACR 1 form: Missouri.

NUCMC data from Univ. of Mo.-Col. Libr., West. Hist. Mss. Coll. and St. Hist. Soc. of Mo. Mss. for Missouri Archaeological Society. Records, 1934-1983 (Missouri Territory)

LC man. auth. cd. (hdg.: Louisiana (District); on the division of the Louisiana purchase in 1804, the part north of 33° received the name District of Louisiana; later chgd. to Territory of Louisiana and in 1812 to Missouri Territory at the time the Territory of Orleans was admitted to the union as the state of Louisiana); hdg.: Louisiana (Ter.); hdg.: Missouri (Ter.))

GeoNames, algorithmically matched, 2009 (adm1; 38°15ʹ01ʺN 092°30ʹ02ʺW)

Laws of a public and general nature : of the District of Louisiana, of the Territory of Louisiana, of the Territory of Missouri, and of the state of Missouri, up to the year 1824, 1842.

Dictionary of United States history, 1894 (Territory of Louisiana; portion of the Louisiana Purchase north of the Territory of Orleans; formed in 1804 as District of Louisiana; 1805 given separate government as Territory of Louisiana; 1812 name changed to Missouri Territory)

Smith, Walter Robinson. Brief history of the Louisiana territory, 1904, viewed online via Internet Archive, May 14, 2014: page 85 (According to the Act of Congress of March 26, 1804, the District of Louisiana passed for one year under the jurisdiction of the Territory of Indiana. In July 1805, the District was organized into Louisiana Territory) page 90 (In 1812 the country north of Louisiana was organized as the Missouri Territory; Missouri was admitted as a state in 1821) page 91 (Arkansas was organized into a separate Territory in 1819) https://ia600301.us.archive.org/11/items/briefhistoryoflo00smit/briefhistoryoflo00smit.pdf

The Louisiana Purchase, c2002: page 267 (For administrative purposes, the region was divided into two territories: the Territory of Orleans and the Louisiana Territory. The Territory of Orleans was that portion of the purchase lands on the western side of the Mississippi River that were south of 33 degrees north latitude, plus the Isle of Orleans. The Louisiana Territory initially encompassed everything else that remainded of the Louisiana Purchase lands above the 33 degree north latitude line) pages 227-228 (After the Territory of Orleans was admitted to the Union in 1812, using the name Louisiana, a portion of the old Louisiana Territory became known as the Missouri Territory; On January 26, 1818, Congress approved a measure to create the Arkansas Territory out of Arkansas County in the Missouri Territory; Missouri Territory sought admission to the Union as a slave state on February 13, 1819; on August 10, 1821, Missouri entered the Union)

Wikipedia, May 14, 2014: Missouri Territory (The Territory of Missouri was an organized incorporated territory of the United States that existed from June 4, 1812 until August 10, 1821, when the southeastern portion of the territory was admitted to the Union as the State of Missouri; The Missouri Territory was originally known as the Louisiana Territory and was renamed to avoid confusion with the new State of Louisiana which joined the Union on April 30, 1812; On March 2, 1819, all of the Missouri Territory south of the parallel 36°30ʹ north, except the Missouri Bootheel between the Mississippi River and the Saint Francis River north of the 36th parallel north, was designated the new Territory of Arkansaw (the spelling of Arkansaw would be changed a few years later); The southeastern portion of the Missouri Territory was admitted to the Union as the State of Missouri on August 10, 1821; The remaining portion of the territory, consisting of the present states of Iowa, Nebraska, and the Dakotas, most of Kansas, Wyoming, and Montana, and parts of Colorado and Minnesota, effectively became an unorganized territory after Missouri became a state. In 1834, the portion east of the Missouri River was attached to the Michigan Territory. Over time, various territories were created in whole or in part from its remaining area: Iowa (1838), Minnesota (1849), Kansas and Nebraska (both 1854), Colorado and Dakota (both 1861), Idaho (1863), Montana (1864), and Wyoming (1868))

List of U.S. state abbreviations, via Wikipedia, September 25, 2015 (Missouri: ISO: US-MO, ANSI: MO, USPS: MO, USCG: MO, Old GPO: Mo., AP: Mo.)