Is that correct to use <strong> if you've already placed the word inside <cite> and want to pay search engines more attention to this? So that word that you usually makes strong but this time this also cite. How to mark up it correct then?
And the additional question what's more correct
<strong><cite>word</cite></strong>
or
<cite><strong>word</strong></cite>
Neither one is invalid but I would go with your first option:
<strong><cite>word</cite></strong>
This usage ties more closely to the word(s) and it allows the strong to emphasize the importance of the citation rather than just the word(s) in the citation.
usage documentation: http://www.whatwg.org/specs/web-apps/current-work/multipage/text-level-semantics.html#the-cite-element
usage documentation: http://www.whatwg.org/specs/web-apps/current-work/multipage/text-level-semantics.html#the-strong-element