Journal of Mathematical Analysis and Applications , 308 (2005), 714-729 http://ac.els-cdn.com/S0022247X04010182/1-s2.0-S0022247X04010182-main.pdf?_tid=dd87c3ea-61f4-11e4-a489-00000aab0f6b&acdnat=1414866684_a8d6e29e4f3f472cd00d7416024adccd
