“…We refer to the books by Peetre [40] and Brudnyǐ and Krugljak [6] and the paper by Nilsson [38] for the basic theory on the general real interpolation method. Other properties of this method can be found, for example, in the papers by Cwikel and Peetre [17], Nilsson [39], Cobos, Fernández-Cabrera, Manzano and Martínez [9], Fernández-Cabrera and Martínez [26] or Cobos, Fernández-Cabrera and Martínez [10].…”