Remove unrelated info

docs/alfreds-essentials-of-music-theory/book-3/unit-13/51-triads-first-inversion.mdx

@@ -30,26 +30,8 @@ From OMT! (more formal attribution in progress!)
 
 - Open Music Theory
   - [Triads](https://viva.pressbooks.pub/openmusictheory/chapter/triads/)
-  - [Major Scales, Scale Degrees, and Key Signatures](https://viva.pressbooks.pub/openmusictheory/chapter/half-and-whole-steps/)
-    - [Major Scales](https://viva.pressbooks.pub/openmusictheory/chapter/major-scales/#chapter-82-section-1)
-    - [Scale Degrees, Solfège, and Scale-Degree Names](https://viva.pressbooks.pub/openmusictheory/chapter/major-scales/#chapter-82-section-2)
 
-### Lessons
+{/* ### Lessons
 
-#### musictheory.net
-
-##### The Basics
-- [Steps and Accidentals](https://www.musictheory.net/lessons/20)
-
-##### Scales and Key Signatures
-- [The Major Scale](https://www.musictheory.net/lessons/21)
-- [Scale Degrees](https://www.musictheory.net/lessons/23)
-
-### Reference
-- Wikipedia
-  - [Key signature](https://en.wikipedia.org/wiki/Key_signature)
-  - [Flat (music)](https://en.wikipedia.org/wiki/Flat_(music))
-- Encyclopedia Britannica
-  - [key signature](https://www.britannica.com/art/key-signature)
-  - [accidental](https://www.britannica.com/art/accidental)
+### Reference */}