bibliotecario in English:

I'm a librarian.

If you can’t find a book in the library, just ask the librarian.

The librarian showed us that we must be quiet.

That librarian had to read lots of books.

A librarian at my high school is very nice

She is a librarian, not a secretary.

The librarian returned with the book I wanted.

I told the librarian that I needed the book for a report due on Friday; so she said she would call it in.