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Update 14.interdisciplinary/40.humanities-art-social-sciences/20.n2/20.propagation-normalisation-amplification-phenomena/40.parallel_1/cheatsheet.fr.md

Update 12.temporary_ins/95.electromagnetism-in-media/10.propagation-lhi-media/10.main/textbook.fr.md

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Update 12.temporary_ins/90.electromagnetism-in-vacuum/20.electromagnetic-waves-vacuum/20.overview/cheatsheet.fr.md