1. Mirra JM, Brien EW. Giant notochordal hamartoma of intraosseous origin: a newly reported benign entity to be distinguished from chordoma. Report of two cases. Skeletal Radiol. 2001;30:698–709.
2. Horwitz T. Chordal ectopia and its possible relation to chordoma. Arch Pathol. 1941;31:354–62.
3. Horwitz T. The human notochord. A study of its development and regression, variations and pathologic derivative, chordoma. Indianapolis: Private printing; 1977.
4. Steegmann AT. Notochordal tissue: its development and reactions. In: Minckler J, editor. Pathology of the nervous system, vol 1. New York: McGraw-Hill; 1968.
5. Willis RA. The borderland of embryology and pathology. 2nd ed. London: Butterworths & Co.; 1962.