I would prefer English books, but Polish would be fine too if nothing exists in English!
I've found this guide with English version:
issuu.com/fabrykautu/docs/przewodnik_09www
Check this out yet:
infinitelegroom.com/2013/05/23/how-to-sail-through-masuria-in-poland/
I had it at home (nice album):
kormoran.sklep.pl/wielkie-jeziora-mazurskie-jerzy-baranowski,id10022.html
Other (Polish) guide books about Great Mazurian Lakes:
rewasz.com.pl