Red blood cell (RBC) volume can be independently determined in vivo in the sheep using ovine RBCs labeled at different densities of biotin. - Mock DM; Matthews NI; Zhu S; Burmeister LF; Zimmerman MB; Strauss RG; Schmidt RL; Nalbant D; Freise KJ; Veng-Pedersen P; Widness JA (Transfusion, 2010)