Penn, Gerald & Hoetmer, Kenneth. 2003. In search of epistemic primitives in the English Resource Grammar (or Why HPSG can’t live without higher-order datatypes). Proceedings of the 10th International Conference on Head-Driven Phrase Structure Grammar 318–337. (doi:10.21248/hpsg.2003.18) (https://proceedings.hpsg.xyz/article/view/572) (Accessed April 27, 2024.)