I know there isn't exactly a surfeit of options if you want a Slovak-English dictionary from Amazon at present, but please - don't make the same mistake I did and order this. It looks hand-typed when you get it, and is out-and-out just WRONG in a fair few situations according to several native Slovak speakers I showed it to. I'm currently taking Slovak classes in Berlitz while I'm in Slovakia and the teachers here know of this dictionary and think it's hysterically bad.
If you need a Slovak-English dictionary, chances are high it's because you're visiting Slovakia for a while. If that's the case, I'd strongly advise buying a Lingea dictionary once you arrive - the Slovaks use them when they learn English and they're SO much better.