 Guest vocalists have included Rush Winters, Billy MacKenzie, Stina Nordenstam, Jade Davies, Shirley Bassey, Heidi Happy and FiFi Rong.The group has shared writing credit with MacKenzie, Winters and Happy.Yello rarely uses samples from previously released music; nearly every instrument has been sampled and re-engineered by Boris Blank, who over the years has built up an original sample library of over 100,000 named and categorised sounds.