Below is a collection of PROc SORT SAS® papers. See also PROC FORMAT.
SAS® Reference PROC SORT Syntax
1. The Problem With NODUPLICATES, Jack Hamilton
2. Checking for Duplicates, Wendi Wright
3. Identifying Duplicate Values, Christopher Bost
4. Finding Duplicate Records in a SAS Dataset, David Franklin
5. Creating Order out of Character Chaos Collation Capabilities of the SAS System, Scott Mebust and Michael Bridgers [SORTSEQ]
6. Identifying Duplicates Made Easy, Elizabeth Guerrero Angel, Yunin Ludena
7. Don’t Waste Too Many Resources to Get Your Data in a Specific Sequence, Henri THEUWISSEN [PRESORTED]
8. A Different View of PROC SORT [Presentation]
9. PROC SORT (then and) NOW, Derek Morgan [SORTSEQ]
10. BY’S NOTSORTED OPTION BY’S NOTSORTED OPTION, Karuna Samudral, Gregory Giddings
11. The Ins and Outs and Ups and Downs of Sorted Data, Andrew Kuligowski [SORTSEQ]
13. Intelligent PROC SORT NODUPKEY, Andrea Zimmerman
14. Removing Duplicates Using SAS, Kirk Paul Lafler
15. Does NODUPKEY Select the First Record in a By Group?, David Franklin