Mapping the circumstellar SiO maser emission in R Leonis R. Soria-Ruiz, J. Alcolea, F. Colomer, V. Bujarrabal and J.-F. Desmurs A&A, 468 1 (2007) L1-L4 Published online: 24 April 2007 DOI: 10.1051/0004-6361:20077554