Cite
MLA Citation
British Standards Institution,. BS EN IEC 61557-9. Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. Equipment for testing, measuring or monitoring of protective measures.. London : British Standards Institution, 2021. http://access.bl.uk/ark:/81055/vdc_100119955530.0x000001