Saadatmand, Mohsen, and Kristiina Kumpulainen. “Content Aggregation and Knowledge Sharing in a Personal Learning Environment: Serendipity in Open Online Networks”. International Journal of Emerging Technologies in Learning (iJET), vol. 8, no. S1, Jan. 2013, pp. pp. 70-78, doi:10.3991/ijet.v8iS1.2362.