You can use either of them at the end of an academic paper (to list your sources). Anyway, if you are writing a paper, you refer to academic sources. In this case you have references:
Since Kihara considers his ‘expectation space theory’ similar to Sperber and Wilson’s (1981) ‘echoic mention theory’ and Sperber and Wilson’s (1986, 1998) ‘echoic interpretation theory’ ...
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