Perhaps you should try some spelling variations:
"Hilbert's texth problem" » "Hilbert's texto problem", "Hilbert's text problem", "Hilbert's texts problem"
"Hilbert's tent problem" » "Hilbert's tenti problem", "Hilbert's text problem", "Hilbert's test 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.

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