The Harvard Kennedy School's Belfer Center published in March 2018 a study titled "Debtbook Diplomacy: China's Strategic Leveraging of its Newfound Economic Influence and the Consequences for U.S. Foreign Policy" by Sam Parker and Gabrielle Chefitz, both MA students at the Kennedy School.
The study does not accuse China of trying to mire Belt and Road Initiative countries in debt. It notes, however, that China loans hundreds of billions of dollars globally and where certain countries, Sri Lanka for example, can not repay the loans, China takes strategic advantage of this situation. The study does not focus on Africa but does include a discussion of China's debt relationship with Djibouti and Kenya.
The China in Africa podcast discussed the report with both authors on 24 June 2018 in a segment titled "A US View on China's So-called 'Debtbook' Diplomacy Agenda."