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\newblock Spectral analysis of {Boolean} functions as a graph eigenvalue
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\newblock {\em IEEE Transactions on Computers}, 48(3):345--351, (1999).

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\newblock {\em J. Combin. Theory Ser. A}, 71(2):241--254, (1995).

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\newblock A theorem of {Hurwitz and Radon} and orthogonal projective modules.
\newblock {\em Proceedings of the American Mathematical Society}, 42(1):51--56,
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\newblock {\"Uber} die {Komposition} der quadratischen {Formen}.
\newblock {\em Math. Ann.}, 88(1-2):1--25, (1922).

\bibitem{Leo16Classifying}
P.~Leopardi.
\newblock {Classifying bent functions by their Cayley graphs}.
\newblock In preparation.

\bibitem{Leo05}
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\newblock A generalized {FFT} for {Clifford} algebras.
\newblock {\em Bulletin of the Belgian Mathematical Society -- Simon Stevin},
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\bibitem{Leo14Constructions}
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\newblock Constructions for {Hadamard} matrices, {Clifford} algebras, and their
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\newblock {\em Australasian Journal of Combinatorics}, 58(2):214--248, (2014).

\bibitem{Leo15Twin}
P.~C. Leopardi.
\newblock Twin bent functions and {Clifford} algebras.
\newblock In {\em Algebraic Design Theory and Hadamard Matrices},  189--199.
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\bibitem{Rad22}
J.~Radon.
\newblock Lineare {Scharen} orthogonaler {Matrizen}.
\newblock {\em Abhandlungen aus dem Mathematischen Seminar der Universit{\"a}t
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\bibitem{Wil44}
J.~Williamson.
\newblock Hadamard's determinant theorem and the sum of four squares.
\newblock {\em Duke Math. J.}, 11:65--81, (1944).

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\newblock Strongly regular graphs and {Hurwitz-Radon} numbers.
\newblock {\em Graphs and Combinatorics}, 6(1):61--69, (1990).

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