| Theravada Man | Manuka | Wijesinghe | 2020 | Literature |
| Theravada Man | Manuka | Wijesinghe | 2009 | Literature |
| Theses in Agricultural Sciences 1976-1987 | University of Peradeniya | N/A | 1988 | General |
| They Call Him Ken, The Life & Times of a Corporate Colossus | Savithri | Rodrigo | 2017 | General |
| They Marched to the Tune of Wings | Kenneth | Reeves | 2009 | General |
| Thimpu Talks, The - The Stand Taken By The Sri Lankan Government | Ministry of State | N/A | 1985 | General |
| Thin Veils in the Shadow of the Gun & the Wicked Witch | Sumathy | N/A | 2003 | Literature |
| Things Seen in Ceylon | C. | Rettie | 1930 | General |
| Things Sinhala | Hemachandra | Senaratne | 2013 | General |
| Third Interim Report of the Special Presidential Commission of Inquiry | Government of Sri Lanka | N/A | 1980 | General |
| Third Interim Report on the Administration of Prisons & Treatment of Prisoners | Govt of Ceylon | N/A | 1938 | General |
| Third Report of the Ceylon Historical Manuscripts Commission | Govt of Ceylon | N/A | 1951 | General |
| Third Woman, The | Punyakante | Wijenaike | 1963 | Literature |
| Third World Dilemma - In the Quest for a New International Economic Order | T.K. | Perera | 1979 | General |
| Thirteenth Amendment to Sri Lanka Constitution - Devolution or Comic Opera ? | Nadesan | Satyendra | N/A | General |
| Thirteenth Amendment to the Constitution (1987) | Govt of Sri Lanka | N/A | 1987 | Politics |
| Thirty Years Along Path of Friendship, Commemorating Diplomatic Relations Between Sri Lanka & China | Sri Lanka-China Society | N/A | 1986 | General |
| Thiruketheeswaram, One of the Pancha - Iswarams of Ancient Sri Lanka | Sanmugam | Arumugam | 2020 | Religion |
| This & That | Elmo | Jayawardena | 2013 | Literature |
| This Demi Paradise This Ceylon | A.A. | Russell | 1969 | General |
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