GilbertL. How to Succeed at Freemium [EB/OL]. [2016-10-20]. .
[5]
Higher Education Funding Council for England. Economic Analysis of Business Models for Open Access Monographs [J]. London Economics,January,2015,3(2):17-19.
[6]
LambertC. The“Wild West”of Academic Publishing—The troubled present and promising future of scholarly communication [J]. Harvard Magazine, January-February, 2015,11(6):53-57.
[7]
LjevakN. “Freemium” Business Models in Publishing: New packaging for the needs of readers in the digital age [J]. Libellarium, 2015,8(10):81-89.