Park SY, Lee ES, Yang YJ, Yoon YS, Lee JH, Huh Y, Park WJ, Cheon JM, Mun JW.  Risk of Hospitalization by Multimorbidity in Middle-Aged Adults Using the 2013–2015 Korea National Health and Nutrition Examination Survey.  KJFP 2021;11:22-28.  https://doi.org/10.21215/kjfp.2021.11.1.22