Perhaps you should try some spelling variations:
"et integral formulation" » "et lineal formulacion", "e integral formulation", "de integral formulation", "la integral formulation"
"_ integral formulation" » "_ lineal formulacion", "e integral formulation"
"de integrales formulation" » "e integrales formulation", "de interes formulation", "de intereses formulation"

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: "((((\"et integral formulation\") OR (\"_ integral formulation\"))) OR (\"de integrales formulation\"))~".
• Removing quotes may allow a broader search: (((( et integral formulation ) OR ( _ integral formulation ))) OR ( de integrales formulation ))~.
• Adding a wildcard symbol may retrieve word variants: (((("et integral formulation") OR ("_ integral formulation"))) OR ("de integrales formulation"))*.