The files are zip'ed versions of the SAS system files, which have the suffix ".ssd01". They can be read into SAS directly and into other packages that can read SAS files (e.g. SPSS).

The data:

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National Longitudinal Survey Data
• Original NLS cohort data (zipped SAS Version 6 system file)
• Recent NLS cohort dat (zipped SAS Version 6 system file)

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• Original NLS cohort data (SAS transport file)
• Recent NLS cohort dat (SAS transport file)

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  Description of data sources, and further information about the data sets, can be found in the book.