The helium weak silicon star HR 7224 - II. Doppler Imaging analysis H. Lehmann, A. Tkachenko, L. Fraga, V. Tsymbal and D. E. Mkrtichian A&A, 471 3 (2007) 941-949 Published online: 18 June 2007 DOI: 10.1051/0004-6361:20077700