APA (7e ed.) Bronvermelding

Roberts, S. (1984). International directory of telecommunications: Market trends, companies, statistics, products, and personnel. Longman.

Chicago (17e ed.) Bronvermelding

Roberts, Steven. International Directory of Telecommunications: Market Trends, Companies, Statistics, Products, and Personnel. Harlow, Essex, UK: Longman, 1984.

MLA (9e ed.) Bronvermelding

Roberts, Steven. International Directory of Telecommunications: Market Trends, Companies, Statistics, Products, and Personnel. Longman, 1984.