Had to sacrifice the drones for a 4th string : r/Rubab
How To Use Drone Strings To Create An Atmospheric Sound On Your Guitar – FuelRocks
Start-up Profile: CyPhy Works Builds Tethered Drones for Soldiers, First Responders - IEEE Spectrum
Adjusting Drone String / Hurdy Gurdy | We're back! This week we discuss how to adjust the drone strings on your hurdy gurdy. Presented by George Leverett of Altarwind Music | By