https://www.google.com.sa/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0ahUKEwiUuZeMhMfSAhWMhRoKHTbED10QFggnMAI&url=https%3A%2F%2Fwww.researchgate.net%2Fpublication%2F282874854_Abstracts_proceeding_of_the27th_Saudi_urological_conferenceSUC&usg=AFQjCNGgcn1UFdQTglzvy8D7zUeRquc1rw
http://www.goldjournal.net/article/S0090-4295(05)01488-3/abstract
http://www.goldjournal.net/article/S0090-4295(06)00902-2/abstract