Japanese wh-phrases as operators with unspecified quantificational force 論文 Mamoru Saitō ·2017-01-12 ·『Language and Linguistics 語言暨語言學』 pp. 1-25 doi:10.1075/lali.18.1.01sai
Operators and Empty Categories in Japanese 論文 Yasuo Ishii ·1991-01-01 ·『Journal of Japanese Linguistics』 13(1) pp. 177-178 doi:10.1515/jjl-1991-0113