diff --git a/quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/tags/references/EventExt.kt b/quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/tags/references/EventExt.kt
index a14d9296e..679879c91 100644
--- a/quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/tags/references/EventExt.kt
+++ b/quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/tags/references/EventExt.kt
@@ -20,19 +20,12 @@
  */
 package com.vitorpamplona.quartz.nip01Core.tags.references
 
-import com.vitorpamplona.quartz.nip01Core.HexKey
 import com.vitorpamplona.quartz.nip01Core.core.Event
 
-fun Event.forEachReferenceTag(onEach: (eventId: HexKey) -> Unit) = tags.forEachReference(onEach)
-
-fun Event.anyReferenceTag(onEach: (str: String) -> Boolean) = tags.anyReference(onEach)
-
 fun Event.hasReferenceTag() = tags.hasReferences()
 
 fun Event.references() = tags.references()
 
-fun Event.isTaggedReference(hashtag: String) = tags.isTaggedReference(hashtag)
+fun Event.isTaggedReference(reference: String) = tags.isTaggedReference(reference)
 
-fun Event.isTaggedReferences(hashtags: Set<String>) = tags.isTaggedReferences(hashtags)
-
-fun Event.firstIsTaggedReferences(hashtags: Set<String>) = tags.firstIsTaggedReferences(hashtags)
+fun Event.isTaggedReferences(references: Set<String>) = tags.isTaggedReferences(references)
diff --git a/quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/tags/references/ReferenceTag.kt b/quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/tags/references/ReferenceTag.kt
index a60167807..8c07af9ff 100644
--- a/quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/tags/references/ReferenceTag.kt
+++ b/quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/tags/references/ReferenceTag.kt
@@ -27,14 +27,34 @@ class ReferenceTag {
         const val TAG_NAME = "r"
         const val TAG_SIZE = 2
 
+        @JvmStatic
+        fun isTagged(
+            tag: Array<String>,
+            reference: String,
+        ): Boolean = tag.size >= 2 && tag[0] == TAG_NAME && tag[1] == reference
+
+        @JvmStatic
+        fun isIn(
+            tag: Array<String>,
+            references: Set<String>,
+        ): Boolean = tag.size >= 2 && tag[0] == TAG_NAME && tag[1] in references
+
+        @JvmStatic
+        fun hasReference(tag: Array<String>): Boolean {
+            if (tag.size < TAG_SIZE || tag[0] != TAG_NAME) return false
+            return tag[1].isNotEmpty()
+        }
+
         @JvmStatic
         fun parse(tag: Array<String>): String? {
             if (tag.size < TAG_SIZE || tag[0] != TAG_NAME) return null
             return tag[1]
         }
 
+        @JvmStatic
         fun assemble(url: String) = arrayOf(TAG_NAME, HttpUrlFormatter.normalize(url))
 
+        @JvmStatic
         fun assemble(urls: List<String>): List<Array<String>> = urls.mapTo(HashSet()) { HttpUrlFormatter.normalize(it) }.map { arrayOf(TAG_NAME, it) }
     }
 }
diff --git a/quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/tags/references/TagArrayExt.kt b/quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/tags/references/TagArrayExt.kt
index c7c74d35a..4a3fb5427 100644
--- a/quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/tags/references/TagArrayExt.kt
+++ b/quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/tags/references/TagArrayExt.kt
@@ -20,26 +20,13 @@
  */
 package com.vitorpamplona.quartz.nip01Core.tags.references
 
-import com.vitorpamplona.quartz.nip01Core.HexKey
 import com.vitorpamplona.quartz.nip01Core.core.TagArray
-import com.vitorpamplona.quartz.nip01Core.core.anyTagged
-import com.vitorpamplona.quartz.nip01Core.core.firstAnyLowercaseTaggedValue
-import com.vitorpamplona.quartz.nip01Core.core.forEachTagged
-import com.vitorpamplona.quartz.nip01Core.core.hasTagWithContent
-import com.vitorpamplona.quartz.nip01Core.core.isAnyLowercaseTagged
-import com.vitorpamplona.quartz.nip01Core.core.isTagged
-import com.vitorpamplona.quartz.nip01Core.core.mapValues
+import com.vitorpamplona.quartz.nip01Core.core.any
 
-fun TagArray.forEachReference(onEach: (eventId: HexKey) -> Unit) = this.forEachTagged(ReferenceTag.TAG_NAME, onEach)
+fun TagArray.hasReferences() = this.any(ReferenceTag::hasReference)
 
-fun TagArray.anyReference(onEach: (str: String) -> Boolean) = this.anyTagged(ReferenceTag.TAG_NAME, onEach)
+fun TagArray.references() = this.mapNotNull(ReferenceTag::parse)
 
-fun TagArray.hasReferences() = this.hasTagWithContent(ReferenceTag.TAG_NAME)
+fun TagArray.isTaggedReference(reference: String) = this.any(ReferenceTag::isTagged, reference)
 
-fun TagArray.references() = this.mapValues(ReferenceTag.TAG_NAME)
-
-fun TagArray.isTaggedReference(hashtag: String) = this.isTagged(ReferenceTag.TAG_NAME, hashtag, true)
-
-fun TagArray.isTaggedReferences(hashtags: Set<String>) = this.isAnyLowercaseTagged(ReferenceTag.TAG_NAME, hashtags)
-
-fun TagArray.firstIsTaggedReferences(hashtags: Set<String>) = this.firstAnyLowercaseTaggedValue(ReferenceTag.TAG_NAME, hashtags)
+fun TagArray.isTaggedReferences(references: Set<String>) = this.any(ReferenceTag::isIn, references)