Mangel AW, Fahim M, van Breemen C. Rhythmic contractile activity of the in vivo rabbit aorta. Nature. 1981 Feb 19;289(5799):692-4.
Mangel AW, Nelson DO, Connor JA, Prosser CL. Contractions of cat small intestinal smooth muscle in calcium-free solution. Nature. 1979 Oct 18;281(5732):582-3.