The Liber Usualis ("The Usual Book") is the most complete book of chant (square-note notation) you can buy for the Tridentine rites. The book contains all of the chant for every feast of the year as well as all special services such as burials, weddings, blessing of Holy Oils, ordinations and benediction. The volume also contains the common chants for the Divine Office and the ordinary chants for the Mass.
The book also contains a wealth of information about how to read and sing chant and the rubrics for all the services in English.
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