Perhaps you should try some spelling variations:
"maximum principles" » "maximum principle"
"maximum principal" » "maximum principle", "minimum principle", "maximal principle"
"maximin principle" » "maximum principle", "main principle", "minimax principle"

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (("maximum principles") OR ((("maximum principal") OR ("maximin principle")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"maximum principles\") or (((\"maximum principal\") OR (\"maximin principle\"))))".
• Removing quotes may allow a broader search: (( maximum principles ) or ((( maximum principal ) OR ( maximin principle )))).
• Adding a wildcard symbol may retrieve word variants: (("maximum principles") or ((("maximum principal") OR ("maximin principle"))))*.