diff --git a/hdx_hapi/db/dao/util/util.py b/hdx_hapi/db/dao/util/util.py
index 5b767744..21dc658d 100644
--- a/hdx_hapi/db/dao/util/util.py
+++ b/hdx_hapi/db/dao/util/util.py
@@ -1,7 +1,7 @@
-from typing import Type
-from sqlalchemy import Column, Select
+from typing import Protocol, Type
+from sqlalchemy import DateTime, Select
+from sqlalchemy.orm import Mapped
 
-from hdx_hapi.db.models.views.all_views import Admin1View, Admin2View, LocationView
 from hdx_hapi.endpoints.util.util import PaginationParams, ReferencePeriodParameters
 
 
@@ -16,10 +16,15 @@ def apply_pagination(query: Select, pagination_parameters: PaginationParams) ->
     return query.limit(limit).offset(offset)
 
 
+class EntityWithReferencePeriod(Protocol):
+    reference_period_start: Mapped[DateTime]
+    reference_period_end: Mapped[DateTime]
+
+
 def apply_reference_period_filter(
     query: Select,
     ref_period_parameters: ReferencePeriodParameters,
-    db_class: Type[LocationView] | Type[Admin1View] | Type[Admin2View],
+    db_class: Type[EntityWithReferencePeriod],
 ) -> Select:
     if ref_period_parameters.reference_period_start_min:
         query = query.where(db_class.reference_period_start >= ref_period_parameters.reference_period_start_min)
@@ -32,6 +37,6 @@ def apply_reference_period_filter(
     return query
 
 
-def case_insensitive_filter(query: Select, column: Column, value: str) -> Select:
+def case_insensitive_filter(query: Select, column: Mapped[str], value: str) -> Select:
     query = query.where(column.ilike(value))
     return query