Ulrike Guelich และ Hans Michael Guelich. (2021) THE IMPORTANCE OF INNOVATION FOR ENTREPRENEURIAL SUSTAINABILITY FOR SOCIAL ENTREPRENEURS IN ASIA-PACIFIC. <i>UTCC International Journal of Business and Economics</i>, <i>13</i>(2), 97-112.Ulrike Guelich และ Hans Michael Guelich. "THE IMPORTANCE OF INNOVATION FOR ENTREPRENEURIAL SUSTAINABILITY FOR SOCIAL ENTREPRENEURS IN ASIA-PACIFIC". UTCC International Journal of Business and Economics 13 (2021):97-112.Ulrike Guelich และ Hans Michael Guelich. THE IMPORTANCE OF INNOVATION FOR ENTREPRENEURIAL SUSTAINABILITY FOR SOCIAL ENTREPRENEURS IN ASIA-PACIFIC. University of the Thai Chamber of Commerce:ม.ป.ท. 2021.