How do I cite a dataset from a database (Datastream)? I have some data that originally is from OECD, but downloaded from the database Datastream. How do I cite this kind of data? I don’t even know the original name of the dataset, just what it’s called in Datastream, which is not necessarily the same thing, right? And what year do I put down?

Edit: Someone edited my title. The original source is not unknown as is clear from the text. I just can't find the data on the OECD website.

Edit2: The topics linked are not about citing third-party databases, which is what I would like an example of. For example, do I call the dataset what it's called in Datastream or do I need to find the original source and find its name? That doesn't seem possible in this case.
A question similar to mine with a satisfying answer can be found here: http://libanswers.brunel.ac.uk/faq/49262