Presumably, a cello quartet is a quartet for 4 cellos, like that by Grazyna Bacewicz (I know also of a suite by Emanuel Moor, and there are other works - quite a few I believe, t hough of course nowhere near as many as there are string quartets as usually defined- by other composers.) I am not familiar, alas, with the content of these works (I hope to be, especially in Bacewicz's case.) -Eric Schissel