WASET
    An Chen and  Huilin Ye,  Multiple-Level Sequential Pattern Discovery from Customer Transaction Databases.   journal   = {International Journal of Computer and Information Engineering}, [online]. World Academy of Science, Engineering and Technology.
    April 2007, vol. 4(4). 1184 - 1192
    [viewed 11 May 2024]. Available from: https://publications.waset.org/pdf/2592.