Official Records
The records of the U.S. District Court for the District of Puerto Rico from 1897-1967 are included among Record Group 21 at the:
National Archives at New York City
One Bowling Green, 3rd Floor
New York, New York 10004
Email: newyork.archives@nara.gov
A guide to the holdings of the regional archives is available at: https://www.archives.gov/nyc/holdings
A published description of the records is also available in the Guide to Federal Records in the National Archives of the United States, 1995 (http://www.archives.gov/research/guide-fed-records/index.html ).
Bibliography
Baralt, Guillermo A. History of the Federal Court in Puerto Rico: 1899-1999. Hato Rey, PR: Publicaciones Puertorriquenas, 2004.