Corpus Mensurabilis Musicae: CMM 4 JACOBUS CLEMENS NON PAPA (ca. 1510-between 1556 and 1558), Opera Omnia, edited by Karel Philippus Bernet Kempers in 21 volumes. Vol. XX Cantiones sacrae ex libris V & VI postume editis Lovanii MDLIX (Series #4) (Paperback)

With foreword, critical notes, and facsimiles. For more information, see http://www.corpusmusicae.com/cmm/cmm_cc004.htm