524 PREFERRED CITATION OF DESCRIBED MATERIALS NOTE (R)Indicators First Display constant controller ^ Cite as 8 No display constant generated Second Undefined; contains a blank (^)Subfield Codes $a Preferred citation of described materials note (NR) $2 Source of schema used (NR) $3 Materials specified (NR) $6 Linkage (NR) $8 Field link and sequence number (R)