How to Tune a 7 String Guitar (Songs, Alternate Tunings, Diagrams) - Guitar Gear Finder
High E string standard guitar tuning (1st string) - YouTube
Video - drop a vs double drop a (7 string vs 9 string guitar)
The Ultimate Guide To 7 String Guitar Tuning - Killer Guitar Rigs
List of guitar tunings - Wikipedia
Double Drop A Song (9 String Guitar) | Double Drop A Song (9 String Guitar) This song was written by Johnny Ciardullo and produced by me. The song was recorded in AEAEADGBE
The Ultimate Guide To 7 String Guitar Tuning - Killer Guitar Rigs