What can be brought to a referendum?

Constitution of the Republic of Poland adopted on 2April 1997

http://www.sejm.gov.pl/prawo/konst/angielski/kon1.htm (in English - the Parliament’s website)

Art. 90 p. 3, art. 125, art. 235 p. 6 

Constitutionalamendments – referendum can be called only if the constitutional amendmentrefers to the provisions of chapter I, II and XII of the Constitution

Adoptionof international treaties, Transfer of authority to international bodies – thesubject of the referendum is to express consent for the President to ratify international agreements, which delegate to aninternational organization or international institution the competence of organsof State authority in relation to certain matters

Other- referendum may be held in respect of matters of particular importance to theState