Secondary sources are studies done by historians and other researchers by analyzing primary sources. Books and journal articles are the main types of secondary sources.
When starting your keyword search to find articles and books, try to do a balanced search—not too broad but not too narrow either. Use several synonyms to be sure that you find everything relevant to your topic. This is very important when you are focusing on just one country, e.g. Cuba, the Dominican Republic, etc.
Image source: Schomburg Center for Research in Black Culture, Photographs and Prints Division, The New York Public Library. "Arthur Schomburg" The New York Public Library Digital Collections. 1896.
Formerly known as International Index to Black Periodicals (IIBP) Full Text
Covers contemporary Latin American and Caribbean history, as well as historical perspective back to the colonial period (15th to 20th century). Provides information about the indigenous peoples of the region, the Conquest (la Conquista), colonial rule, religion, struggles for independence, and political, economic, and social progress and issues in newly independent nations. Contains pages of historical material from archival collections in the United States and Europe. Provides original manuscripts, signed letters, expedition records, reports, maps, diaries, descriptions of voyages, ephemera, and more.