ISBN 600313423123.
Having been asked for years to prepare a TTB/TBB/TTBB version of his classic work for SATB, Thompson was convinced that it could not be done without destroying the fabric of the piece. One day, 28 years later, he realized it had been written unintentionally in four-part invertible counterpoint. Note by note, the inversion of the voices could be chosen to preserve the original melodies and harmonies.
