North, Ernest J.; Millard, Sollie M.(Innovatio Publishers (Germany), Media Tenor (South Africa) and the Institute for Media Analysis in South Africa (Imasa), 2003)
Green, Robin J.; Feldman, Charles; Schoub, Barry D.; Richards, Guy A.; Madhi, Shabir A.; Zar, Heather J.; Lalloo, Umesh G.(Health and Medical Publishing Group, 2008-03)