The European Space Agency (ESA) is Europe's gateway to space. Its mission is to shape the development of Europe's space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world.

European Space Agency

The reference for Global Navigation Satellite Systems NAVIPEDIA is an initiative of the European Space Agency aiming at becoming the reference for Global Navigation Satellite Systems general knowledge on the Internet

European Space Agency - Navipedia

US Department of Homeland Security - United States Coast Guard The Navigation Center operates services and provides information that enhances the safety, security, and efficiency of US waterways and civil GPS users.

US Coastguard Navigation Centre