A sensitive survey for 13CO, CN, H2CO, and SO in the disks of T Tauri and Herbig Ae stars S. Guilloteau, E. Di Folco, A. Dutrey, M. Simon, N. Grosso and V. Piétu A&A, 549 (2013) A92 Published online: 03 January 2013 DOI: 10.1051/0004-6361/201220298