Q. What are Green Papers and White Papers?

These are consultation documents produced by Government departments to gather feedback on changes to policy (Green Papers) and to outline legislative proposals or draft Bills (White Papers, which often follow a Green Paper and are sometimes called Command Papers. Command Papers are numbered in sequence). 

The parliament.uk website offers an excellent glossary of key terms here, including Acts of Parliament, Bills and Debates.

For some referencing examples, try the Institute of Education subject guide, under the Government resources tab.