T. Gordh J:r and L. Wiklund, “A Method for Reliable and Simultaneous Cannulation of the Epidural and Subarachnoid Spaces in Pigs: A tool for the study of cerebrospinal fluid pharmacakinetics and drug penetration of the dura mater”, ujms, vol. 91, no. 1, pp. 111-115, Mar. 1986.