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OCLC Support

Number phrase search

Discover how to perform a number phrase search when searching WorldCat indexes.


Any number that is part of a record's bibliographic information that you can use to retrieve the records you need. The system finds the number in an indexed field.

Index label format

xx= (where x represents an alphanumeric character)


  • NLM Class Number — lm=hq 1381 c524w 1976
  • Music/Publisher Number — mn=co1979ab51


  • Most efficient way to search for these types of numbers:
  • A number search can retrieve a single record (e.g., by its unique ISBN) or precisely related records (e.g., by class number). Numbers are usually unique to a single record or group of related records.
  • Type all numbers and letters.
  • Omit spaces.
  • Omit punctuation, except keep periods (.) in classification numbers.
  • When entering ISBNs ending in x — If you use the number keypad, truncate the number using the asterisk key (*).