“…Recently, many studies have been devoted to questions of regularity under Zhikov's [61] and Fan's [20] logarithmic condition, when λ(r) L < +∞ in (1.5)-(1.7) (see e.g. [1,[5][6][7][8]12,15,16,21,23,35,46,47,50,57]), and now the elliptic theory has reached a completely satisfactory form (see original surveys [29,41,42,48] and monograph [49]). In general, the logarithmic condition has significantly advanced the theory of function spaces with variable exponents [17,19], which are an integral part of the generalized Orlicz (Musielak-Orlicz) spaces [27,45].…”