The 2008 release is a corrected reprint of the 2002 third typical edition promulgated by . While not a completely new edition, it introduced several critical updates that remain standard today:
That said, there are — for purchase or subscription — and free public domain excerpts (e.g., the Ordo Missae of the 1970 Missal is not copyrighted in its Latin chant form by some publishers? Actually, be careful: the 2002/2008 text is still protected).
The Ordo Missae (Order of Mass) and chant sections are often made available by monasteries, seminaries, or academic projects for study. For example: