@conference {, title = {Spotting Symbol over Graphical Documents via Sparsity in Visual Vocabulary}, booktitle = {Recent Trends in Image Processing and Pattern Recognition (Part of CCIS book series, Vol 709, page 59-70)}, year = {2016}, month = {December }, publisher = {Springer }, organization = {Springer }, doi = {10.1007/978-981-10-4859-3} }