See this legally free ebook:

  • The Mass: A Study of the Roman Liturgy, by Adrian Fortescue [1874-1923] (London, New York, Toronto, Bombay, Calcutta, Madras: Longmans, Green and Co., 1922). May be read online, and available in pdf, mobi, epub, and other formats, at Internet Archive.

See also the texts listed on the page Liturgy and on the posts ‘Free ebooks: “Holy Mass: The Eucharistic Sacrifice and the Roman Liturgy”, by Rev. Herbert Lucas (in 2 volumes)‘, ‘Worth-it ebook: “The Genius and Timeliness of the Traditional Latin Mass”, by Peter Kwasniewski‘, and ‘Resources on the Traditional (Pre-1955) Holy Week Liturgy of the Roman Rite‘.

On the Feast of Pope St. Pius V in the Roman Rite. For other texts and ebooks, you may access the List of Free eBooks (Arranged by Title), the List of Free eBooks (Grouped by Subject), the List of Worth-It Catholic Books & eBooks, and the main page of the Catholic eBooks Project.