Estatísticas das comunicações 1992-1996
Communications outlook 1997 / Organisation for Economic Co-Operation and Development
Les chiffres clés et indicateurs des télécommunications mondiales : 1997
Perspectives des communications 1997 [texto policopiado] / Organisation for Economic co-Operation and Development
Yearbook of statistics : telecommunication services: chronological time series 1986-1995 / International Telecommunication Union