A citation for a consulted source in which information is found about the 1XX heading in an
established heading record. The information found in the source may also be present.
Each additional source of information is recorded in a separate 934 note.
$a - Source citation (NR). In UNBIS, the entire note is recorded in subfield $a.
934 $a Tesauro de la Unesco
934 $a Google search
934 $a Tesauro Popin
934 $a http://www.probert-encyclopaedia.com/sp-eng-m.htm