Perhaps you should try some spelling variations:
"Hilbert's bento problem" » "Hilbert's abierto problema"
"Hilbert's test problem" » "Hilbert's text problem", "Hilbert's west problem", "Hilbert's best problem"
"Hilbert's teets problems" » "Hilbert's tenets problems", "Hilbert's tweets problems", "Hilbert's texts problems", "Hilbert's teets problemas", "Hilbert's teets problema"

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 test problem") OR ("Hilbert's bento problem"))) OR ("Hilbert's teets problems"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"Hilbert's test problem\") OR (\"Hilbert's bento problem\"))) OR (\"Hilbert's teets problems\"))".
• Removing quotes may allow a broader search: (((( Hilbert's test problem ) OR ( Hilbert's bento problem ))) OR ( Hilbert's teets problems )).
• Adding a wildcard symbol may retrieve word variants: (((("Hilbert's test problem") OR ("Hilbert's bento problem"))) OR ("Hilbert's teets problems"))*.