[
[1] J. Aczél and J. Dhombres, Functional Equations in Several Variables. With Applications to Mathematics, Information Theory and to the Natural and Social Sciences, Encyclopedia of Mathematics and its Applications, 31, Cambridge University Press, Cambridge, 1989.
]Search in Google Scholar
[
[2] B. Ebanks, The cosine and sine addition and subtraction formulas on semigroups, Acta Math. Hungar. 165 (2021), no. 2, 337–354.
]Search in Google Scholar
[
[3] B. Ebanks, Around the sine addition law and d’Alembert’s equation on semigroups, Results Math. 77 (2022), no. 1, Paper No. 11, 14 pp.10.1007/s00025-021-01548-6
]Search in Google Scholar
[
[4] B. Ebanks and H. Stetkær, d’Alembert’s other functional equation on monoids with an involution, Aequationes Math. 89 (2015), no. 1, 187–206.
]Search in Google Scholar
[
[5] H. Stetkær, Functional Equations on Groups, World Scientific, Singapore, 2013.10.1142/8830
]Search in Google Scholar
[
[6] H. Stetkær, Extensions of the sine addition law on groups, Aequationes Math. 93 (2019), no. 2, 467–484.
]Search in Google Scholar
[
[7] H. Stetkær, Homomorphisms of product semigroups, Results Math. 77 (2022), no. 2, Paper No. 60, 21 pp.10.1007/s00025-022-01603-w
]Search in Google Scholar
[
[8] W.H. Wilson, On certain related functional equations, Bull. Amer. Math. Soc. 26 (1920), no. 7, 300–312.
]Search in Google Scholar
