Sankoff and Cedergren 1983

Sankoff D & Cedergren RJ (1983) Simultaneous comparison of three or more sequences related by a tree. In Sankoff D & Kruskal JB, editors., Time Warps, String Edits, and Macromolecules: The Theory and Practice of Sequence Comparison, pp. 253-263. Addison-Wesley, Reading, Massachusetts.