Perhaps you should try some spelling variations:
"index models mathematical" » "index modern mathematical", "index modelling mathematical", "index modern mathematics", "index model mathematical", "induced models mathematical"
"index soils mathematical" » "index bonds mathematical", "index fields mathematical", "index cycles mathematical", "index fossils mathematical", "indian soils mathematical", "index social mathematical"
"index models mathematics" » "index model mathematics", "index modern mathematics", "index modeling mathematics", "induced models mathematics"

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((("index models mathematical") OR ("index soils mathematical"))) or ("index models mathematics"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("index models mathematical") OR ("index soils mathematical"))) OR ("index models mathematics")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"index models mathematical\") OR (\"index soils mathematical\"))) or (\"index models mathematics\"))".
• Removing quotes may allow a broader search: (((( index models mathematical ) OR ( index soils mathematical ))) or ( index models mathematics )).
• Adding a wildcard symbol may retrieve word variants: (((("index models mathematical") OR ("index soils mathematical"))) or ("index models mathematics"))*.