diff --git a/src/agent.ts b/src/agent.ts
index a39e38d..bb21e95 100644
--- a/src/agent.ts
+++ b/src/agent.ts
@@ -995,7 +995,8 @@ But unfortunately, you failed to solve the issue. You need to think out of the b
       SchemaGen,
       80,
       maxRef,
-      minRelScore
+      minRelScore,
+      onlyHostnames
     );
 
     answerStep.answer = answer;
diff --git a/src/tools/build-ref.ts b/src/tools/build-ref.ts
index a99ad0e..f1acdd6 100644
--- a/src/tools/build-ref.ts
+++ b/src/tools/build-ref.ts
@@ -3,6 +3,7 @@ import {Reference, TrackerContext, WebContent} from "../types";
 import {Schemas} from "../utils/schemas";
 import {cosineSimilarity, jaccardRank} from "./cosine";
 import {getEmbeddings} from "./embeddings";
+import {normalizeHostName} from '../utils/url-tools';
 
 export async function buildReferences(
   answer: string,
@@ -11,7 +12,8 @@ export async function buildReferences(
   schema: Schemas,
   minChunkLength: number = 80,
   maxRef: number = 10,
-  minRelScore: number = 0.7
+  minRelScore: number = 0.7,
+  onlyHostnames: string[] = []
 ): Promise<{ answer: string, references: Array<Reference> }> {
   console.log(`[buildReferences] Starting with maxRef=${maxRef}, minChunkLength=${minChunkLength}, minRelScore=${minRelScore}`);
   console.log(`[buildReferences] Answer length: ${answer.length} chars, Web content sources: ${Object.keys(webContents).length}`);
@@ -30,6 +32,7 @@ export async function buildReferences(
   let chunkIndex = 0;
   for (const [url, content] of Object.entries(webContents)) {
     if (!content.chunks || content.chunks.length === 0) continue;
+    if (onlyHostnames.length > 0 && !onlyHostnames.includes(normalizeHostName(url))) continue;
 
     for (let i = 0; i < content.chunks.length; i++) {
       const chunk = content.chunks[i];