diff --git a/.env.example b/.env.example
index 959034c7..65e05d8e 100644
--- a/.env.example
+++ b/.env.example
@@ -15,6 +15,7 @@ ORCID_ID_SEARCH_API=https://pub.orcid.org/v2.1/search
 ORCID_ID_EMPLOYMENT_API=https://pub.orcid.org/v3.0/{orcid_id}/employments
 ORCID_ID_PERSON_API=https://pub.orcid.org/v3.0/{orcid_id}/person
 CM_API=https://api.naturalproducts.net/latest/
+CROSSREF_API=https://api.crossref.org/works/
 
 
 LOG_CHANNEL=stack