Publishing organisation. Year of publication/last updated. Title of extract. Available at: URL [Accessed: day month year].
Example:
BHP Billiton. 2017. BHP Billiton sustainability report for the year ended 30 June 2017. Available at: https://www.bhp.com/-/media/documents/investors/annual- reports/2017/bhpsustainabilityreport2017.pdf? [Accessed: 2 May 2018].