Hi, I'm interested in mapping the LCSH topics described in Library of
Congress book records to the "predefined headings" LCSH thesaurus
defined at

For example, the MODS version of the LoC record for isbn 1606238760
contains this LCSH info:

  <subject authority="lcsh">
    <topic>Social sciences</topic>
    <topic>Statistical methods</topic>
    <topic>Data processing</topic>

... which maps neatly to "sh2010113695" (Social sciences--Statistical
methods--Data processing) (see

However, not all topics map to a single shNNNN code (multiple shNNNN's
with the same description), and some topics have no shNNNN code at (e.g. "Discourse analysis--Research", even though
"Discourse analysis" exists)

Is there a way to retrieve the shNNNN codes directly for a book
record? I'm currently using the LoC SRU (search/retrieval via URL)
service, but it only serves verbose, "textual" <topic>s that must be
mapped separately to a shNNNN code (when possible)