diff --git a/nvchecker_source/bitbucket.py b/nvchecker_source/bitbucket.py
index c3716d9..c93a3fe 100644
--- a/nvchecker_source/bitbucket.py
+++ b/nvchecker_source/bitbucket.py
@@ -1,10 +1,9 @@
 # MIT licensed
 # Copyright (c) 2013-2020 lilydjwg <lilydjwg@gmail.com>, et al.
 
-from nvchecker.api import sort_version_keys
-
-# doc: https://confluence.atlassian.com/display/BITBUCKET/commits+or+commit+Resource
+# doc: https://developer.atlassian.com/cloud/bitbucket/rest/api-group-commits/#api-repositories-workspace-repo-slug-commits-get
 BITBUCKET_URL = 'https://bitbucket.org/api/2.0/repositories/%s/commits/%s'
+# doc: https://developer.atlassian.com/cloud/bitbucket/rest/api-group-refs/#api-repositories-workspace-repo-slug-refs-tags-get
 BITBUCKET_MAX_TAG = 'https://bitbucket.org/api/2.0/repositories/%s/refs/tags?sort=-target.date'
 
 async def get_version(name, conf, *, cache, **kwargs):