See this legally free ebook:

  • Conferences on the Blessed Trinity, by the Rev. Dr. J.J. O’Connell, O.S.B. (New York: Catholic Publication Society, 1882). With Imprimatur. May be read online, and available in pdf, epub, kindle/mobi, Daisy, djvu, and txt formats at Open Library and Internet Archive.

On the Feast of St. Eusebius of Vercelli in the Extraodinary Form of the Roman Rite. For other legally free ebooks, you may access the List of Free eBooks (Arranged by Title) and the List of Free eBooks (Grouped by Subject). Holy Trinity, one God, have mercy on us!