All revelant 3GPP (3rd Generation Partnership Project) Mobile Communications Standards can be found at 3GPP.
NGMN (Next Generation Mobile Networks) was founded to further develop the LTE-Advanced and 5G Mobile Communications.
All ITU (International Telecommunication Union) Standards can be found at ITU.
5G PPP (5G Public Private Partnership) was founded by private companies and EU, in order to push the 5G studies and standaradization 5G PPP.
IETF Internet Engineering Task Force coordinates the internet standaradization IETF.