NY Times Historical database is especially invaluable as a source of primary documentation, since it has the full text of the newspaper 1851-2004. (More recent NY Times can be found in Lexis.)
But, there is another major newspaper of record, a British paper; The Times of London. (That's their logo at the top of the page.) We don't have it in an online database, but we do have it in microfilm, 1785-1998 (more recent years in Lexis.) The Times came up just today, someone was looking for it for articles on the Congo Free State, the Belgian colony of the early 1900s. You can find the microfilm of the Times in the microfilm room on the ground floor, past the copiers and the quiet study room. There are indexes on top of the cabinets to the Times, and if you need more help just ask one of us.