diff --git a/lit/aktive-filter-und-oszillatoren-entwurf-und-schaltungstechnik-mit-integrierten-bausteinen_compress.pdf b/lit/aktive-filter-und-oszillatoren-entwurf-und-schaltungstechnik-mit-integrierten-bausteinen_compress.pdf
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diff --git a/lit/lit.csv b/lit/lit.csv
index e486dd8..18af692 100644
--- a/lit/lit.csv
+++ b/lit/lit.csv
@@ -1 +1,6 @@
-NAME;LINK
+NAME;LINK
+www.schmitzbits.de;https://www.schmitzbits.de/vco2.html
+www.burosch.de;https://www.burosch.de/en/audio/1169-labor-blaetter-band-2-otas-grundlagen-und-anwendungen.html
+www.birthofasynth.com;https://www.birthofasynth.com/Thomas_Henry/Pages/VCO-1_resources.html
+www.synthesizeracademy.com;http://synthesizeracademy.com/voltage-controlled-amplifier-vca/
+www.electrical4u;https://www.electrical4u.com/voltage-controlled-oscillator/
diff --git a/lit/vca_handout.pdf b/lit/vca_handout.pdf
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