Works referring to the datasets or codebooks should contain a citation in the following style:

National Center for Health Statistics (<i>Issue Year</i>).  Data File Documentations,
Natality, <i>Data Year</i> (machine readable data file and documentation, CD-ROM Series
<i>Series</i>, No. <i>No.</i>), National Center for Health Statistics, Hyattsville, Maryland.

where the italicized fields are filled in with the appropriate information below:

Data            Issue  Series  No.
Year		Year
1991 		1997	21	5
1992		1996	21	2
1993		1997	21  	3
1994		1997	21	4
1995		1998	21	6
	

Tables derived from the data should have a cite at the bottom like this:
Source:  National Center for Health Statistics (span of years used)

The published material should also include a disclaimer that credits any
analyses, interpretations, or conclusions reached to the author (recipient of
the data file) and not to NCHS, which is responsible only for the initial data.