diff --git a/source/src/main/java/one/nem/lacerta/source/database/dao/Document.java b/source/src/main/java/one/nem/lacerta/source/database/dao/Document.java
new file mode 100644
index 00000000..f0c7f646
--- /dev/null
+++ b/source/src/main/java/one/nem/lacerta/source/database/dao/Document.java
@@ -0,0 +1,4 @@
+package one.nem.lacerta.source.database.dao;
+
+public interface Document {
+}
diff --git a/source/src/main/java/one/nem/lacerta/source/database/dao/Library.java b/source/src/main/java/one/nem/lacerta/source/database/dao/Library.java
new file mode 100644
index 00000000..2bce89a0
--- /dev/null
+++ b/source/src/main/java/one/nem/lacerta/source/database/dao/Library.java
@@ -0,0 +1,4 @@
+package one.nem.lacerta.source.database.dao;
+
+public interface Library {
+}
diff --git a/source/src/main/java/one/nem/lacerta/source/database/dao/Tag.java b/source/src/main/java/one/nem/lacerta/source/database/dao/Tag.java
new file mode 100644
index 00000000..c3c2536e
--- /dev/null
+++ b/source/src/main/java/one/nem/lacerta/source/database/dao/Tag.java
@@ -0,0 +1,4 @@
+package one.nem.lacerta.source.database.dao;
+
+public interface Tag {
+}