Karo to Rudy Vallee in 13 Steps
- Karo wrote Crois-Tu Vraiment
- Crois-Tu Vraiment was published by Unichappell Music
- Unichappell Music published Little Cowboy
- Little Cowboy was published by Six Continents Music
- Six Continents Music published La Cancion Del Cachorro
- La Cancion Del Cachorro was written by Harry Nilsson
- Harry Nilsson sang Thanks for the Memory
- Thanks for the Memory was produced by Derek Taylor
- Derek Taylor produced It Had to Be You
- It Had to Be You appeared in the film Show Business
- Show Business is a 1944 film starring Eddie Cantor
- Eddie Cantor was the first singer to record Makin' Whoopee!
- Makin' Whoopee! was recorded by many artists including Rudy Vallee