Tones for the Prophecy, Epistle, and Gospel may be found beginning on p. 102 of Liber Usualis. There are others sources, but this may be the most immediately available. (For any who may be unaware, LU is available as a reprint from the St Bonaventure Press for about $125.)
There is a site that's done much of the work, but it's geared to the extraordinary form. Hopefully it shouldn't be too hard to find what you need. http://www.windsorlatinmass.org/latin/chant.htm
The most up to date book is the third edition of the latin Missale Romanum, which contains in the appendix all the actual melodies for readings, with explication. The Missale is large format, published in Rome, but also - in an own version - in the States.
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