The image behind the breviary pages during Lent are from the Les Très Riches Heures du duc de Berry, Folio 199v. The file was downloaded from the image's page at Wikimedia Commons and is in the public domain.
The images behind the breviary pages during Ordinary time are from British Library, Royal 2 B XV, f. 45v and 16r. The files were downloaded from the manuscript's page at Wikimedia Commons and are in the public domain.
The core text of the breviary comes from the 1979 American Book of Common Prayer. It is in the public domain. The traditional language psalter is from the 1928 American Book of Common Prayer, also in the public domain.
The ordinary antiphons on the psalms are drawn from the abbreviated Psalter compiled by Saint Bede. He excerpted a line or two from each psalm to form one long psalm drawn from the rest that could be memorized and prayed as a compendium of the psalter as a whole.
The Sunday antiphons on the Gospel canticles are the work of Tom Kostrzewa, OblSB CAM and are used with his generous permission.
The festal antiphons on both the psalms and the canticles are drawn primarily from the Marquis of Bute's translation of the Tridentine Breviary which is in the public domain. Occasions for which there were no antiphons in the Tridentine Breviary were created by myself in consultation with a variety of works including the Anglican Breviary, A Monastic Breviary, and the English Office.
The hymns largely follow the Sarum order as found in The Hymner. The text for the traditional-language hymns were drawn from the Oremus Hymnal and the NetHymnal. I believe that all of the hymns are in the public domain. Contemporary-language hymns are from the Order of Julian of Norwich's hymnal and are used with the kind permission of Fr. John-Julian, OJN.
New Revised Standard Version Bible, copyright 1989, Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved. The New Revised Standard Version Bible may be quoted and/or reprinted up to and inclusive of five hundred (500) verses without express written permission of the publisher, provided the verses quoted do not amount to a complete book of the Bible or account for fifty percent (50%) of the total work in which they are quoted.