User-agent: Yandex
Disallow: /preview/*
Disallow: /_sys-dynamic
Disallow: /r?
Clean-param: nw&from&text&amp

User-agent: Googlebot
Disallow: /preview/*
Disallow: /_sys-dynamic
Disallow: /r?

User-agent: *
Disallow: /preview/*
Disallow: /_sys-dynamic
Disallow: /r?