http://www.google.com.co/imgres?imgurl=http://82.194.83.116/multimedia/12/200808/Bullterrier_0001.JPG&imgrefurl=http://www.cachorrosplus.com/producto.aspx%3Fmn%3D2%26cn%3D23&usg=__hXh8Be1UWGk9FvQyhZKUXj8S_e8=&h=622&w=929&sz=62&hl=es&start=113&zoom=1&tbnid=Oha336X02v7zwM:&tbnh=136&tbnw=163&prev=/images%3Fq%3Dbull%2Bterrier%26hl%3Des%26biw%3D1360%26bih%3D581%26gbv%3D2%26tbs%3Disch:10%2C2508&itbs=1&iact=rc&dur=538&ei=vf30TJi-NYL58Aae0_HeBQ&oei=rv30TITQNcOBlAfLjc3EBQ&esq=6&page=6&ndsp=22&ved=1t:429,r:17,s:113&tx=69&ty=83&biw=1360&bih=581
sacado de: http://www.youtube.com/watch?v=t_4RmRoWMXk
