If you have access to an online bibliographic database, a university catalog, or a bibliographic database on CD-ROM, you can probably use EndNote’s import filters to import text files saved or downloaded from these sources. EndNote filters are configurable so they give you the flexibility to import the reference data you need, and eliminate data you do not need.
There are two main things you need to know in order to correctly import downloaded references into EndNote:
How to download the data in the right output format. See Getting Data in the Right Format.
Which import filter to use to import the data into EndNote. See Choosing the Correct Import Filter.
The table in Summary of Output Formats and Corresponding Import Options summarizes a number of common sources of bibliographic data, the instructions for downloading tagged files, and the EndNote import option to use to import the references into EndNote.