According to Zaide, there are documents and printed matter in his collection that cannot be found elsewhere, not even in the Filipiniana Division of The National Library nor in any library the world over, the Library of Congress of the United States included. The best years of his life were spent in looking for them only to find them after an almost "wild goose chase" of a lifetime. His Rizaliana collections were greatly acknowledged by W. E. Retana, James A. Le-Roy, and Austin Craig.