What to Read in the Morning? A Niche Analysis of Free Daily Papers and Paid Papers in Korea - Yi, Keunyeong and Sung, Yoontaek (International Journal on Media Management, 2007)
https://katalog.adlr.link/Record/ai-49-aHR0cDovL2R4LmRvaS5vcmcvMTAuMTA4MC8xNDI0MTI3MDcwMTYzNDE1NQ