@article{articlebbfaad8c,
title   = {Enhancement of the epidural morphine-induced analgesia by systemic nifedipine},
author = {Pereira, I L T and Prado, W A and Reis, M P},
year = {1993},
doi = {10.1016/0304-3959(93)90230-m},
journal   = {Pain}
}