The United Nations produces many reports that are released as sales publications. In general, sales publications are not part of the depository documents however we may have purchased a sales publication separately. These items may or may not include a document symbol number.
Example: This record from Readex AccessUN is for a sales publication with no document symbol number.
The record in the Cornell Library Catalog:
Search for the title (not the symbol number) in the library catalog or the Worldcat union catalog. Note: If a sales publication also includes a document symbol number, there is a small chance that it was filmed by Readex for the microfiche or microcard collections.
If the item is not found in a library catalog search AccessUN to see if the document is included in the Readex UN Microcard/Microfiche collection (1946 - 2009).