Complex sentence: In 1987 Awareness Records released a cassette of "Lifemask" (AWT 1007) containing 4 bonus tracks, however these tracks were not included on the 1990 Awareness Records CD (AWCD 1007) release.
Split into simpler sentences: In 1987 Awareness Records released a cassette of "Lifemask" (AWT 1007) containing 4 extra tracks. These tracks cannot be found on the 1990 Awareness Records CD (AWCD 1007) release.