Perhaps you should try some spelling variations:
"bases constitucionales de apertura" » "aspectos constitucionales de apertura" (Expand Search), "limites constitucionales de apertura" (Expand Search), "organos constitucionales de apertura" (Expand Search), "bases constitucionales en apertura" (Expand Search), "bases constitucionales la apertura" (Expand Search)
"bases constitucionales y apertura" » "aspectos constitucionales y apertura" (Expand Search), "limites constitucionales y apertura" (Expand Search), "organos constitucionales y apertura" (Expand Search), "bases constitucionales la apertura" (Expand Search)

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• Performing a fuzzy search may retrieve terms with similar spellings: (("bases constitucionales de apertura") OR ("bases constitucionales y apertura"))~.
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• Adding a wildcard symbol may retrieve word variants: (("bases constitucionales de apertura") OR ("bases constitucionales y apertura"))*.