R. AliMohammadzadeh and  M. Haghir Chehreghani and  A. Zarnani and  M. Rahgozar,  W3-Miner: Mining Weighted Frequent Subtree Patterns in a Collection of Trees.   journal   = {International Journal of Computer and Information Engineering}, [online]. World Academy of Science, Engineering and Technology.
    July 2008, vol. 19(7). 2489 - 2492
    [viewed 15 October 2019]. Available from: https://publications.waset.org/pdf/13085.