His most important work is Notitia utriusque Vasconiae, tum Ibericae, tum Aquitanicae, qua praeter situm regions et alia scitu digna (1638 and 1656), a description of Gascony and Navarre.
His collection of 537 Basque proverbs or adages, Atsotizac edo Refravac, included in a volume of his poems Gastroa Nevrthizetan, printed in Paris in 1657 under the French title Les Proverbes Basques Recueillis Par Le Sr D’Oihenart, Plus Les Poesies Basques du mesme Auteur, was supplemented by a second collection, Atizen Venquina.
The proverbs were edited by Francisque Xavier Michel (1847), and the supplement by P.
Hariston (1892) and by V.
Stempf (1894).See Julien Vinson, Essai d'une bibliographie de la langue basque (Paris, 1891); J.
B.
E.
de Jaurgain, Arnaud d'Oihenart et sa famille (Paris, 1885).