He continued his theological studies at Erfurt, Tübingen and Basel before returning to Augsburg as director (Magister) of the Gymnasium.
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In 1545 Betuleius published at Basel an edition of eight books of the Sibylline oracles with a preface dating from perhaps the sixth century.
In 1545 Xystus Betuleius (Sixt Birck of Augsburg) published at Basel an edition of eight books of oracles with a preface dating from perhaps the 6th century AD, and the next year a version set in Latin verse appeared.