The term grey literature is used to describe a wide range of different information that is produced outside of traditional publishing and distribution channels, like library book, journal and database collections.
You may well want to look at grey literature in the form of information posted on websites of companies, institutions and interest groups about banking law related topics. This information can typically be posted just to websites and is not formally published in any other way.
Grey literature sources can be very useful sources in terms of their uniqueness and currency but can also have some drawbacks in terms of quality and longevity of information. To find out more about the types of grey literature, the pros and cons of this type of information and hints and tips on searching for this information, take a look at the Grey Literature Libguide.
