User-agent: Googlebot
Allow: /
Disallow: /*.pdf

User-agent: Googlebot-Image/1.0
Allow: /
Disallow: /*.pdf

User-agent: Bingbot
Allow: /
Disallow: /*.pdf

User-agent: Slurp
Allow: /
Disallow: /*.pdf

User-agent: facebot
Allow: /
Disallow: /*.pdf

User-agent: DuckDuckBot
Allow: /
Disallow: /*.pdf

User-agent: ia_archiver
Allow: /
Disallow: /*.pdf

User-agent: archive.org_bot
Allow: /
Disallow: /*.pdf

User-agent: NinjaBot
Allow: /
Disallow: /*.pdf

User-agent: *
Disallow: /