Antonio Zavala publishes his foundational anthology of Basque bertsolaritza (improvised oral verse), collecting thousands of bertso (folk quatrains) from rural improvisers (bertsolaris). These poems draw on Basque mythology (lamiak, mairuak) and pre-Christian folklore, employing strict rhyme and meter schemes (zortziko txikia). The collection revitalizes Basque oral poetry suppressed under Franco's dictatorship.

Zavala's collection fueled the resurgence of bertsolaritza competitions, influencing Basque poets (Gabriel Aresti, Bernardo Atxaga) to fuse oral improvisational forms with written poetry against cultural erasure. The bertso's folk logic and community performance model reshaped Basque literary poetics, proving that endangered language poetry survives through folklore's collective transmission. It remains taught as a model of orality-to-literacy poetics.