"i really know" acappella orig?

anybody know where the original vocal is taken from? used on these tracks (and lots of others)

http://www.discogs.com/League-Of-Nat...release/435481

http://www.discogs.com/Regina-Lee-I-...release/515734

http://www.discogs.com/Blue-Violet-I...release/767007

http://www.discogs.com/artist/203330-Melody-Stars-The

Alisha Warren - Touch Me

brilliant , thanks for that, it was doing my head in