Here are the links to the LOP specific Rules and regulations:

Golf Cart Rules 

Golf Course Rules 

In 2016, the USGA decided to allow the Rules of Golf to be accessed during play via the USGA Rules of Golf App

In addition, in 2016 Revision to Rule 14-3: Use of Artificial Devices and Unusual Equipment; Abnormal Use of Equipment can be found here.

This video is worth watching for clarity.

In conjunction with the changes to the Rules of Golf effective January 1, 2016, specifically the Local Rule permitting the use of distance-measuring devices under Rule 14-3, the USGA and The R&A are providing recommendations to assist manufacturers and developers of laser rangefinders, GPS devices, mobile GPS applications and other electronic Distance-Measuring
Devices (DMDs).

If you are considering using a DMD you should be aware of the need for a Local Rule to allow for these. Each club / torunament can define there own Local Rule  In addition, please be aware that some mobile apps are illegal to use.

Here is the notice to device Manufactures which is interesting to read for clarity.
“Questions will arise if permitted and prohibited functions are not effectively separated on the device.”