Galaxy zoo 2: Detailed morphological classifications for 304,122 galaxies from the sloan digital sky survey

K.W. Willett, C.J. Lintott, S.P. Bamford, K.L. Masters, B.D. Simmons, K.R.V. Casteels, E.M. Edmondson, L.F. Fortson, S. Kaviraj, W.C. Keel, T. Melvin, R.C. Nichol, M. Jordan Raddick, K. Schawinski, R.J. Simpson, R.A. Skibba, A.M. Smith, D. Thomas