I'm working on app that should be installed only on phones and not tablets. 

I want to ask, how can I restrict to install only on phones?

I was reading this article, but it seems pretty old to me:
[Distributing to Specific Screens](http://developer.android.com/guide/practices/screens-distribution.html#FilteringTabletApps)

They are not talking about xxhdpi or xxxhdpi resolutions at all and devices are divided by screen size. It could work few years ago, but now? For example Nexus 6 has 6" screen size - it can be considered almost like tablet. 

Do you know any working solution?