Non-empty box counting algorithm for calculating fractal dimensions and its applications in EEG analysis. - F. H. Ling; N. Xu; J. H. Xu (Neural Networks, 1988)

TREC-6 English and Chinese Retrieval Experiments using PIRCS. - K. L. Kwok; Laszlo Grunfeld; J. H. Xu (TREC, 1997)