Cite
HARVARD Citation
Institution,, B. (1992) BS 6789-6.1:1986. Apparatus with one or moreparticular functions for connection to certain public switchedtelephone networks. Specification for series connectedapparatus. Apparatus having maximum allowable impairments".. [Online]. London : British Standards Institution. Available from: http://access.bl.uk/ark:/81055/vdc_100104117002.0x000001