"TTCSP Global Go To Think Tank Index Reports | Think Tanks and Civil Societies Program (TTCSP) | University of Pennsylvania". repository.upenn.edu.
اطلع عليه بتاريخ 11 يونيو 2017.  "TTCSP Global Go To Think Tank Index Reports | Think Tanks and Civil Societies Program (TTCSP) | University of Pennsylvania". repository.upenn.edu (باللغة الإنجليزية).