The Second Vatican Council gave a possibility and requirement to create a national folk liturgical song. Council designated the Gregorian Choral as an ideological model and determined his most important sources: The Holy Scripture and the liturgical texts. The new creation has mission 'deeper into sources of liturgy'. The form and content of the new tradition has a pattern in 'Graduale Romanum' or 'Graduale simplex'. The new tradition is inspired by the liturgical value of the antiphon's texts. Formally is similar to antiphon and is inspired by it, therefore we call it quasi-antiphon. The main purpose of this paper is substantiate the new tradition and present the principles for the theological selection of verses of a new tradition.