Spiros Nikolopoulos Eirini Giannakidou Ioannis Kompatsiaris Ioannis Patras Athena Vakali Combining Multi-modal Features for Social Media Analysis. 71-96 2011 Social Media Modeling and Computing http://dx.doi.org/10.1007/978-0-85729-436-4_4 books/daglib/0026652 db/books/daglib/0026652.html#NikolopoulosGKPV11