Li, H.; Chen, Z.: 'Overview of different wind generator systems and their comparisons', IET Renewable Power Generation, 2008, 2, (2), p. 123-138, DOI: 10.1049/iet-rpg:20070044 IET Digital Library, https://digital-library.theiet.org/;jsessionid=3bu6jdpwi18n8.x-iet-live-01content/journals/10.1049/iet-rpg_20070044