[Descriptive comparison of serum progesterone levels during intravaginal device insertion in mares] oleh A.C.B. Teixeira, J.A.N. Riveros, I.C. Pereira, B. R. Martins, L.L. Ledo, M. F. Brito, G.A. Monteiro, F. P. Leme, L.Z. Oliveira