http://www.genetics.org/content/150/3/1115 (Abstract)
Castresana, J., Feldmaier-Fuchs, G., Yokobori, S.-i., Satoh, N., & Pääbo, S. (1998). The mitochondrial genome of the hemichordate Balanoglossus carnosus and the evolution of deuterostome mitochondria. Genetics, 150(3), 1115-1123.