One of the books I have been looking at in Lent is Theological and Historical aspects of the Roman Missal. This is the published version of the papers given at the fifth international CIEL Conference, which was held at Versailles in the autumn of 1999.
The Roman Missal
The 1884 editio typica in a printing of 1911
I know or have heard several of the contributors and the papers make for extremely good reading. They are not only erudite and informative, and indeed thought provoking on liturgical and historical matters, but also have a reflective quality that makes them good material to use at this season of the year.
I learned a lot from the volume - the authors draw upon the great body of scholarly work that has been done on the history of the Roman Rite, and make available a not inconsiderable number of fascinating details and interpretations which I had either not known or fully appreciated hitherto.