diff --git a/articles/Airy disk - Wikipedia/Airy disk - Wikipedia.pdf.txt b/articles/Airy disk - Wikipedia/Airy disk - Wikipedia.pdf.txt
new file mode 100644
index 0000000..2d90c02
--- /dev/null
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diff --git a/articles/Airy disk - Wikipedia/Airy disk - Wikipedia.xopp.xml b/articles/Airy disk - Wikipedia/Airy disk - Wikipedia.xopp.xml
new file mode 100644
index 0000000..9701152
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