Luna, Carlos Andrés, Rubén Tulcán-Toro, Felipe Romero, and Mario Fernando Luna. 2017. “Measurement of Residual Volume in Spinal Needles After Spinal Anesthesia”. Colombian Journal of Anesthesiology 45 (Supplement), 12-15. https://www.revcolanest.com.co/index.php/rca/article/view/178.