- Original Articles Patient's Perception of Symptoms Related to Morning Activity in Chronic Obstructive Pulmonary Disease: The SYMBOL Study
- Yeon Jae Kim, Byung Ki Lee, Chi Young Jung, Young June Jeon, Dae Sung Hyun, Kyung Chan Kim, Sung Ken Yu, Hye Sook Choi, Won Hyuk Shin, Kwan Ho Lee
- Korean J Intern Med. 2012;27(4):426-435.