must be default in firefox!! thanks, really only the way to add missed search engines! <3
Here is my answer:
@How to add a custom search engine to Firefox?@

https://superuser.com/questions/7327/how-to-add-a-custom-search-engine-to-firefox/1474187#1474187

and here as well:
@Firefox: add Google search engine - why no such option in search/address bar?@
https://superuser.com/a/1549586/230571