User-agent: Googlebot
Disallow: /*.gif$
User-agent: Googlebot
Disallow: /*.jpg$
User-agent: Googlebot
Disallow: /*.png$
User-Agent: Googlebot-Image
Disallow: /
User-agent: Googlebot
Disallow: /*.pdf$
User-agent: Googlebot
Disallow: /*.doc$
User-agent: Googlebot
Disallow: /*.txt$