Searching for chameleon-like scalar fields with the ammonia method S. A. Levshakov, P. Molaro, A. V. Lapinov, D. Reimers, C. Henkel and T. Sakai A&A, 512 (2010) A44 Published online: 30 March 2010 DOI: 10.1051/0004-6361/200913007