Different people and institutions use different systems of referencing so if you are referencing for a school or university assignment it would be advisable to contact your department or teacher first. Referencing for footnotes and for a bibliography also varies.
Otherwise OnThisDay.com recommends the following for a bibliography entry.
Electronic Sources e.g. Web sites
General Format: Last name, First name of author or editor, Title, Edition, Place of publication, Date of publication, Medium, Available protocol: Site/Path/File (if relevant), Access date (if relevant).
e.g. for OnThisDay.com:
Graham, James, 'China's growing trade with European ships 1517-1800', OnThisDay.com, online, 2002, available at: http://www.onthisday.com/asia/china_trade.php (21 July 2002)