 Most of the documents in this enormous collection had not previously been translated into English.Volumes 15 and 16 consist of Antonio de Morga's "History of the Philippine Islands From Their Discovery by Magellan in 1521 to the Beginning of the XVII Century", an extremely valuable source on the early history of the islands.Her last work was the translation and editing of documents for "The Indian Tribes of the Upper Mississippi Valley and Region of the Great Lakes" (2 vols., 1911–12).