“…By an Olsen inequality, or a trace inequality, we mean an inequality of type (1.2) g · I α f X ≤ C g Y · f Z for some Banach function spaces X, Y and Z, where I α f is the Riesz potential (of order α) of f . There is a vast amount of literatures on Olsen inequalities [11,12,28,29,30,32,33,34,36]. We shall show that (1.2) holds with X = Z = L Φ (R N ) and a certain Morrey space Y .…”