<http://schema.org/query-input>
"required name=search_term_string"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.audible.com/pd/Language-Instruction/113-Common-TOEFL-Words-and-Examples-Audiobook/B00DN98016?ref_=cat_22266_c10_4_t>