Ayres T.R., J.R. Stauffer, T. Simon, R.A. Stern, S.K. Antiochos, G.S. Basri, J.A. Bookbinder, A. Brown, G.A. Doschek, J.L. Linsky, and L.W. Ramsey, The Astrophysical Journal 420, L33 (1994).