diff --git a/articles/Frequency response - Wikipedia/Frequency response - Wikipedia.pdf.txt b/articles/Frequency response - Wikipedia/Frequency response - Wikipedia.pdf.txt
new file mode 100644
index 0000000..d01a6a4
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+++ b/articles/Frequency response - Wikipedia/Frequency response - Wikipedia.pdf.txt	
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diff --git a/articles/Frequency response - Wikipedia/Frequency response - Wikipedia.xopp.xml b/articles/Frequency response - Wikipedia/Frequency response - Wikipedia.xopp.xml
new file mode 100644
index 0000000..d161e5f
--- /dev/null
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