Perhaps you should try some spelling variations:
"Hilbert's veinte problemas" » "Hilbert's veinte poemas", "Hilbert's fuentes problemas", "Hilbert's en problemas"
"Hilbert's tenth problem" » "Hilbert's tenti problem", "Hilbert's tent problem", "Hilbert's teeth problem"
"Hilbert's benth problem" » "Hilbert's beth problem", "Hilbert's bento problem", "Hilbert's bench problem"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (((("Hilbert's tenth problem") OR ("Hilbert's benth problem"))) OR ("Hilbert's veinte problemas"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"Hilbert's tenth problem\") OR (\"Hilbert's benth problem\"))) OR (\"Hilbert's veinte problemas\"))".
• Removing quotes may allow a broader search: (((( Hilbert's tenth problem ) OR ( Hilbert's benth problem ))) OR ( Hilbert's veinte problemas )).
• Adding a wildcard symbol may retrieve word variants: (((("Hilbert's tenth problem") OR ("Hilbert's benth problem"))) OR ("Hilbert's veinte problemas"))*.