Department Administrative Order No. 12, Series of 2008
Mandatory Philippine National Standard related to the use of LPG and CNG in Motor Vehicles

BPS Memo Circular No. 04 Series of 2009
Time Table for the Implementation of PNS UN ECE 115::2006 – Uniform Provisions Concerning the Approval of: Specific Liquefied Petroleum Gas (LPG) and CNG (Compressed Natural Gas) Retrofit Systems to be installed in Motor Vehicles for the use of LPG or CNG, respectively in their Propulsion System

BPS Memorandum 106 series of 2008
Clarification on the PS License Issued to Motor Vehicle LPG Conversion Shop

Standardization Circular 03-83 Standardization of Automotive Liquefied Petroleum Gas (LPG) Steel Cylinders for Use in Motor Vehicles covered by PNS 04:1983, Gas cylinders for automotive - LPG for use in motor vehicles - Steel cylinders – Specifications