“…Later, Castro, Córdoba and Gómez-Serrano [6] proved the existence of V-states for the range α ∈ [1, 2) and obtained the C ∞ -regularity of their boundary for all α ∈ (0, 2), see also [7] for the real analyticity of the patch boundary. For other connected topics we refer to the papers [1,5,6,24,22,31,33,42] and the references therein.…”