Update README.md added reference links

Kirby collection, bf:MusicMedium

README.md

@@ -35,11 +35,13 @@ Note! There are several possibly problematic concepts due to overlapping distrib
   * Asia
     * Sound of Asia https://www.soundofasia.com/ (Commercial company)
     * Terms in North Indian music https://chandrakantha.com/glossary/
+  * Africa
+    * Percival Kirby Musical Instruments https://ibali.uct.ac.za/s/pkmi/ (University of Cape Town)
  * And many more...
 
 # BIBFRAME
 
-For mapping purposes the appropriate concepts in SEKO3 could be marked as instances of <b><a href="https://id.loc.gov/ontologies/bibframe.html#c_MusicEnsemble">bf:MusicEnsemble</a></b>  or <b><a href="https://id.loc.gov/ontologies/bibframe.html#c_MusicInstrument">bf:MusicInstrument</a></b>. 
+For mapping purposes the appropriate concepts in SEKO3 could be marked as instances of <b><a href="https://id.loc.gov/ontologies/bibframe.html#c_MusicEnsemble">bf:MusicEnsemble</a></b>  or <b><a href="https://id.loc.gov/ontologies/bibframe.html#c_MusicInstrument">bf:MusicInstrument</a></b> or <br><a href="https://id.loc.gov/ontologies/bibframe.html#c_MusicMedium">bf:MusicMedium</a></b>. 
 
 # Wikidata mappings