Academie Royale des sciences d'outre-mer
Has a list of their publications. Many full text publications are free online. For example - Bulletin des séances. https://www.kaowarsom.be/catalog/index.php
 

Belgique, Congo, Rwanda et Burundi : guide des sources de l'histoire de la colonisation (19e-20e siècle) : vers un patrimoine mieux partagé !
sous la direction de Pierre-Alain Tallier, Marie Van Eeckenrode et Patricia Van Schuylenbergh
Turnhout, Belgium : Brepols, [2021]
2 volumes (2294 pages) : illustrations, maps ; 27 cm
Lane Reading Room
https://searchworks.stanford.edu/view/14015104

Vol 1.  1156 pages
Vol 2. Pages 1157-2294

Has Indices for Keywords, Places, archival institutions.
Chronology 1884-1962
List of all Ministers of Colony 1908-1961
Congo Independent State 1885-1958 Administrator Governors
Has a directory of all institutions cited and a large number of photographs, copies of letters, documents, posters.

This title is available online and can be downloaded.

 

Biographie belge d'outre-mer
9 volumes.   Biographies of individuals during the colonial era.  . Followed by Biographical Dictionary of Overseas Belgians. https://www.kaowarsom.be/en/bbom
 

Confidential U.S. State Department central files. Congo, 1960-January 1963 [microform] : internal affairs, decimal numbers 755A, 770G, 855A, 870G, 955A, and 970G, and foreign affairs, decimal numbers 655A, 670G, 611.55A, and 611.670G.

Imprint: Bethesda, MD : University Publications of America, c2000.
Physical Description: 40 microfilm reels ; 35 mm. + 1 guide.
Subject (LC): Congo (Democratic Republic)--History--1960-1997--Sources.
Subject (LC): Congo (Democratic Republic)--Foreign relations--1960-1997--Sources.
Covers the road to Congolese independence and "the Belgian Congo's turbulent path to nation building with some 40,000 pages of State Department" material. See a 134 page User's Guide in PDF.  
https://searchworks.stanford.edu/view/7723098

 

Congo Mission archives [microform] : the papers of Bishop Ridsdale (1916-2000) : missionary to the Eastern Congo, from the Henry Martyn Centre, Cambridge​
Description on the Adam Matthew website. 
Author: Ridsdale, Philip, 1916-2000
Imprint: Marlborough, Wiltshire, England : Adam Matthew Publications, 2006. 
Physical Description: 6 microfilm reels : ill. ; 35 mm 
Note: Reel 1 includes a guide to reel contents. 
Notes: Guide is also available in digital form from the Adam Matthew Publications website. 
Notes: Documents chiefly in English, with some in French and Swahili. 
Subject (LC): Church of England--Missions--Congo (Democratic Republic)--History--20th century--Sources. 
Subject (LC): Church of England--Congo (Democratic Republic)--History--20th century--Sources. 
Library has: reel 1-6 
GREEN CALL NUMBER, COPY LOCATION:  MFILM N.S. 16576  MEDIA-MTXT

 

Congo Missionary Messenger
HOOVER--Location: STACKS copy 1 
Library has: 1929-1937,1940-1946,1956-1962
HOOVER CALL NUMBER,  LOCATION: 
1)SERIAL:USA 1929-1937  STACKS 
2)SERIAL:USA 1940-1944 STACKS 
3)SERIAL:USA 1945-1946 STACKS 
4)SERIAL:USA 1956-1959 STACKS 
5)SERIAL:USA 1960-1962 STACKS
https://searchworks.stanford.edu/view/357713

 

[J. M. Derscheid collection of materials on Rwanda and Burundi, 1877-1933] [microform].
In French, German. 4 microfilm reels ; 35 mm There are two different versions. Stanford has a less complete version. University of Florida owns the original collection which is the most complete.

 

Despatches from U.S. Consuls in Boma, Congo, 1888-1895
In Searchworks go to Nineteenth Century collections online [electronic resource].
Select the Archive - Europe and Africa: Commerce, Christianity, Civilization, and Conquest
Page down to -  Despatches from U.S. Consuls in Boma, Congo, 1888-1895
The 324 page manuscript is in cursive.

 

[Documents found in the archives of the Region of Shaba of the Republic of Zaire].
Imprint: [Shaba, Zaire : Thomas Q. Reefe, 1972?].
Physical Description: 6 microfilm reels ; 35 mm. + Prospectus (4 leaves : map ; 28 cm.)
Note: "Contains copies of over 350 documents ... written by Belgian administrators ... from 1906 to the 1950's. The microfilms were made as part of a Ph. D. dissertation research project into ... the Luba empire ... centered in the present-day administrative district of the Sous-region du Haut Lomami..."--Prospectus, p. [1].
Subject (LC): Comité spécial du Katanga--History--Sources.
Subject (LC): Luba (African people)--History--Sources.
Subject (LC): Katanga (Congo)--History--Sources.
HOOVER  LIBRARY       6 microfilm reels
1) DT665.K3 A15 MFILM       MICROFILM
2) DT665.K3 A15 PROSPECTUS      STACKS
https://searchworks.stanford.edu/view/1905304

 

Money, Duncan - Sources for the History of the Copperbelt
Archival sources for the colonial and post-colonial history of the Democratic Republic of the Congo and Zambia.
"state archives, company archives, trade union archives, missionary archives, international organisations, personal archive collections, newspapers, photographs and films. Duncan Money is a historian of Central and Southern Africa based at Leiden University, Netherlands.  He manages a project to preserve and digitize the archives of the Mineworkers’ Union of Zambia.
https://duncanmoney.wordpress.com/sources-for-the-history-of-the-copperbelt/

Records of the Department of State relating to internal affairs Congo [microform] : political and governmental affairs, February 1963-1966. Subject numeric file POL. CORPORATE AUTHOR United States. Department of State   LANGUAGE English.
Woodbridge, CT : Primary Source Media, Gale Cengage Learning
40 microfilm reels ; 35 mm. + 1 guide.
Gale Primary Source Media Guide online, 50 pages. Covers both Congo-Brazzaville and Congo-Leopoldville.

Zaire Church News.
Former title: Congo mission news1912-June 1970 Former title: Congo church news July 1970-Sept. 1971
Imprint: Kinshasa.
Volume/date range: no. 1- ; Nov. 1912-
Notes: Issued 1912- by the Church of Christ in Zaire (called 1912-Mar. 1970, Congo Protestant Council; Apr. 1970-Sept. 1971, Church of Christ in Congo)
Subject (LC): Missions--Congo (Democratic Republic)
Subject (LC): Protestant churches--Congo (Democratic Republic) Organization: Congo Protestant Council.
GREEN--Location: STACKS
Library has: [1-234, 1912-72]
GREEN CALL NUMBER BV3625 .C6 C6
https://searchworks.stanford.edu/view/401026