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\bibitem{Clark_etal2016} {\textquotedblleft}\textit{Symmetry-constrained electron vortex propagation}{\textquotedblright}. Clark L, Guzzinati G, B{\'e}ch{\'e} A, Lubk A, Verbeeck J, Physical review A \textbf{93}, 063840 (2016).   http://doi.org/10.1103/PhysRevA.93.063840

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