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