On the Functional Equation f(λ)+f(ωλ)f(ω -1 λ)=1, (ω 5 =1)
Les rencontres physiciens-mathématiciens de Strasbourg -RCP25, Tome 34 (1984), Exposé no. 4, 13 p. 
@article{RCP25_1984__34__91_0,
     author = {Sibuya, Yasutaka},
     title = {On the {Functional} {Equation} $f(\lambda )+f(\omega \lambda )f(\omega ^{-1}\lambda )=1$, $(\omega ^5=1)$},
     journal = {Les rencontres physiciens-math\'ematiciens de Strasbourg -RCP25},
     note = {talk:4},
     pages = {91--103},
     publisher = {Institut de Recherche Math\'ematique Avanc\'ee - Universit\'e Louis Pasteur},
     volume = {34},
     year = {1984},
     language = {en},
     url = {http://www.numdam.org/item/RCP25_1984__34__91_0/}
}
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Sibuya, Yasutaka. On the Functional Equation $f(\lambda )+f(\omega \lambda )f(\omega ^{-1}\lambda )=1$, $(\omega ^5=1)$. Les rencontres physiciens-mathématiciens de Strasbourg -RCP25, Tome 34 (1984), Exposé no. 4, 13 p. http://www.numdam.org/item/RCP25_1984__34__91_0/

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