This book by Mary Vander Woude (edited by the great Philip Farkas) opens with a series of “pre-virtuoso” studies designed to prepare the student for the virtuoso works of the trumpet. With each succeeding etude, conventional musical restrictions have been gradually removed until the player is permitted almost complete freedom from traditional form. A mode of writing – explained in the appendices – not used before in composiiton, has been created to allow for this liberation from usual technical restraints. The pieces themselves are marvels of rhythmic complexity and interpretive sophistication.
Check out the first few in the samples then grab this wonderful collection at the link above.