A secondary source is something that is created after an event has occurred, often by someone who did not experience or participate in the event. Common secondary sources include books, journal articles, reference sources, and documentaries.
There are a number of library databases that may contain secondary sources on the Gillespie tour. Some of them are likely familiar to you already.
Check out the Library Search which finds print and electronic items, including journal and newspaper articles, book chapters, books, reviews, legal documents, and much more. Note: Due to licensing restrictions, some content is only available to current students, faculty, and staff.
International index of journal articles, books, conference proceedings, reviews, catalogs, and dissertations, primarily in the areas of musicology, ethnomusicology, music theory, and analysis.