Perhaps you should try some spelling variations:
"Hilbert's en problemas" » "Hilbert's y problemas", "Hilbert's de problemas", "Hilbert's a problemas"
"Hilbert's tenth problem" » "Hilbert's tenti problem", "Hilbert's tent problem", "Hilbert's benth problem"
"Hilbert's test problem" » "Hilbert's text problem", "Hilbert's west problem", "Hilbert's best 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 test problem"))) OR ("Hilbert's en problemas"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"Hilbert's tenth problem\") OR (\"Hilbert's test problem\"))) OR (\"Hilbert's en problemas\"))".
• Removing quotes may allow a broader search: (((( Hilbert's tenth problem ) OR ( Hilbert's test problem ))) OR ( Hilbert's en problemas )).
• Adding a wildcard symbol may retrieve word variants: (((("Hilbert's tenth problem") OR ("Hilbert's test problem"))) OR ("Hilbert's en problemas"))*.