Ian Grieve gives us Microsoft Dynamics GP 2013 SP2 Web Client Scale-Out Deployment: Creating Required Service Accounts
Microsoft Dynamics GP 2013 SP2 Web Client Scale-Out Deployment: Creating Required Service Accounts | azurecurve
Install, Upgrade & AdminMicrosoft & the GP EcosystemGP 2013
Archived post from 2014. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.