Changju Lee and Seungmo Ku and Sondo Kim and Woojin Chang, Detecting Financial Bubbles Using Gap between Common Stocks and Preferred Stocks. journal = {International Journal of Economics and Management Engineering}, [online]. World Academy of Science, Engineering and Technology. January 2017, vol. 122(2). 301 - 307 [viewed 19 September 2024]. Available from: https://publications.waset.org/pdf/10006194.