Alexander S. Kechris. Forcing With /triangle Perfect Trees and Minimal /triangle-Degrees. Journal of Symbolic Logic, 46(4):803-816, 1981.
@article{Kechris81, title = {Forcing With /triangle Perfect Trees and Minimal /triangle-Degrees}, author = {Alexander S. Kechris}, year = {1981}, researchr = {https://researchr.org/publication/Kechris81}, cites = {0}, citedby = {0}, journal = {Journal of Symbolic Logic}, volume = {46}, number = {4}, pages = {803-816}, }