Perhaps you should try some spelling variations:
modification » modificacion, codificacion, modificaciones
edificacion » modificacion, certificacion, purificacion
certification » certificacion, versification, stratification
identification » identificacion, identificaron, identifican
fortification » stratification, certificacion, purification

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((modification or edificacion) or ((certification OR identification) or fortification))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((modification OR edificacion) OR ((certification OR identification) OR fortification)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((modification or edificacion) or ((certification OR identification) or fortification))".
• Adding a wildcard symbol may retrieve word variants: ((modification or edificacion) or ((certification OR identification) or fortification))*.