Ph. Barbe, W. P. McCormick, and C. Zhang，Asymptotic expansions for distributions of compound sums of random variables with rapidly varying subexponential distribution.Journal of Applied Probability, Volume 44, Number 3 (2007), 670-684.
http://projecteuclid.org/DPubS?verb=Display&version=1.0&service=UI&handle=euclid.jap/1189717537&page=record