Analysis of information sources in references of the Wikipedia article "Pietas" in Vietnamese language version.
pietatem, quae erga patriam aut parentes aut alios sanguine coniunctos officium conservare moneatas quoted by Wagenvoort, Hendrik (1980). Pietas: Selected Studies in Roman Religion. Studies in Greek and Roman Religion. 1. Brill. tr. 7. ISBN 9004061959.