It often happens that you have only part of a reference to something - either you forgot to take down the publisher details, or you decide to use a resource which you didn't think you were going to use when you first saw it. In these circumstances, 'backward referencing' (I made this word up) is very easily done using online catalogues.

Example: What you remember: "That video of Les Sylphides by the Kirov with Asylmuratova"

Method:

1. Go to the online catalogue of the New York Public Library - you will get the screen shown below.

2. Select the option to search in "Words in Title, Subject etc." field. Don't use the "Title" field, because "Les Sylphides" may not be in the title at all - the video might have been called "The Glory of The Kirov" or some such thing.

3. Now type in

(Les Sylphides) Asylmuratova

as shown below. Note that you should use brackets, rather than quotation marks to indicate to the search engine that the exact phrase 'Les Sylphides' should be searched for.

4. With any luck, you should now get a screen like the one below:

5. Click on one of the recordings to see the full details

6. If you click on "The Maryinsky Ballet" , for example, you'll get a whole page of information, probably more than you'll ever need, about the video in question. You can check if it's the one you saw, and take down details which you need.

WHAT TO DO IF YOU DON'T FIND THE VIDEO YOU WANT

1. Go back to the "Search for Words in Title etc.." page.

2. Type in less terms: i.e. just

Les Sylphides

or just

Asylmuratova

3. You'll get a list of probably over 500 works containing the words "Les Sylphides".

4. Press which is on the top right hand side of the screen.

5. You'll see a list of things that you can limit, click on the downward arrow next to the word material type. Select "PROJ MATERIAL" by clicking on it with the mouse, as shown below:

6. Now press the Limit/Sort items button (shown below)

7. Click on titles you retrieve, to see if they are what you wanted.