Perhaps you should try some spelling variations:
"index model mathematical" » "index models mathematical", "index modern mathematical", "index modeling mathematical"
"index carus mathematical" » "index circuits mathematical", "index cards mathematical", "index cases mathematical", "index card mathematical"
"index models mathematics" » "index model mathematics", "index models mathematical", "index modern mathematics", "induced models mathematics"

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: (((("index model mathematical") OR ("index carus mathematical"))) OR ("index models mathematics"))~.
• Removing quotes may allow a broader search: (((( index model mathematical ) or ( index carus mathematical ))) or ( index models mathematics ))~.
• Adding a wildcard symbol may retrieve word variants: (((("index model mathematical") or ("index carus mathematical"))) or ("index models mathematics"))*.