diff --git a/src/core/article.h b/src/core/article.h
index 990ea1f..b30e293 100644
--- a/src/core/article.h
+++ b/src/core/article.h
@@ -16,6 +16,7 @@ class Article : public EntityUuid
   public:
     Article() = default;
     Article(int price);
+    Article(const Article&) = delete;
     virtual ~Article() = default;
 
     void setArticleNo(int articleNo);
diff --git a/src/core/sale.h b/src/core/sale.h
index 0cfb18c..02a960d 100644
--- a/src/core/sale.h
+++ b/src/core/sale.h
@@ -17,6 +17,9 @@ using ArticlesVec = std::vector<Article*>;
 class Sale : public EntityUuid
 {
   public:
+    Sale() = default;
+    Sale(const Sale&) = delete;
+    virtual ~Sale() = default;
     void addArticle(Article* articlePtr);
     void setTimestamp(const std::string& timestamp);
 
diff --git a/src/core/seller.h b/src/core/seller.h
index 0c84958..0c6dd38 100644
--- a/src/core/seller.h
+++ b/src/core/seller.h
@@ -14,6 +14,7 @@ class Seller : public EntityInt
 {
   public:
     Seller() = default;
+    Seller(const Seller&) = delete;
     virtual ~Seller() = default;
     Seller(const std::string& firstName, const std::string& lastName, int sellerNo = 0,
            int numArticlesOffered = 0);