Keefe, G., Squires, E. J., Walsh, R., Wilson, J. B. and Leslie, K. E. (2006) “Impact of a progesterone-releasing intravaginal device on plasma progesterone levels in lactating dairy cattle”, The Bovine Practitioner, 40(2), pp. 108–111. doi: 10.21423/bovine-vol40no2p108-111.