On substitution invariant Sturmian words: an application of Rauzy fractals Valérie Berthé, Hiromi Ei, Shunji Ito and Hui Rao RAIRO-Theor. Inf. Appl., 41 3 (2007) 329-349 Published online: 25 September 2007 DOI: 10.1051/ita:2007026