Kimble R.A., B.E. Woodgate, C.W. Bowers, S.B. Kraemer, M.E. Kaiser, T.R. Gull, S.R. Heap, A.C. Danks, A. Boggess, R.F. Green, and J.B. Hutchings, The Astrophysical Journal 492, L83 - L93 (1998).
Yang L.X., G. Rohde, T. Rohwer, A. Stange, K. Hanff, C. Sohrt, L. Rettig, R. Cortés, F. Chen, L. Feng, and T. Wolf, Physical Review Letters 112, 207001 (2014).