A KOSMA 7 deg CO 2–1 and CO 3–2 survey of the Perseus cloud - I. Structure analysis K. Sun, C. Kramer, V. Ossenkopf, F. Bensch, J. Stutzki and M. Miller A&A, 451 2 (2006) 539-549 Published online: 02 May 2006 DOI: 10.1051/0004-6361:20054256