diff --git a/src/core/sale.cpp b/src/core/sale.cpp
index 43ecabb..92b0140 100644
--- a/src/core/sale.cpp
+++ b/src/core/sale.cpp
@@ -4,6 +4,7 @@
 
 void Sale::addArticle(std::shared_ptr<Article> articlePtr)
 {
+    articlePtr->setSale(this);
     articles_.push_back(articlePtr);
 }
 
diff --git a/src/core/seller.cpp b/src/core/seller.cpp
index 94d3a0d..d2dc247 100644
--- a/src/core/seller.cpp
+++ b/src/core/seller.cpp
@@ -3,13 +3,13 @@
 Seller::Seller() : Entity() {}
 
 Seller::Seller(const std::string& firstName, const std::string& lastName, int sellerNo,
-               int numberOfArticles)
+               int numArticlesOffered)
     : Entity()
 {
     firstName_ = firstName;
     lastName_ = lastName;
     sellerNo_ = sellerNo;
-    numberOfOfferedArticles_ = numberOfArticles;
+    numArticlesOffered_ = numArticlesOffered;
 }
 
 void Seller::setSellerNo(int seller_no) { sellerNo_ = seller_no; }
@@ -18,11 +18,13 @@ inline void Seller::setFirstName(const std::string& firstName) { firstName_ = fi
 
 inline void Seller::setLastName(const std::string& lastName) { lastName_ = lastName; }
 
-inline void Seller::setNumberOfOfferedArticles(int number) { numberOfOfferedArticles_ = number; }
+inline void Seller::setNumArticlesOffered(int number) { numArticlesOffered_ = number; }
 
-int Seller::getNumberOfOfferedArticles() const { return static_cast<int>(articles_.size()); }
-
-void Seller::addArticle(std::shared_ptr<Article> article) { articles_.push_back(article); }
+void Seller::addArticle(std::shared_ptr<Article> article)
+{
+    article->setSeller(this);
+    articles_.push_back(article);
+}
 
 std::string Seller::getFirstName() const { return firstName_; }
 
@@ -43,4 +45,8 @@ std::vector<Article*> Seller::getArticles(bool onlySold) const
     return articles;
 }
 
-size_t Seller::soldArticles() const { return getArticles(true).size(); }
\ No newline at end of file
+int Seller::numArticlesSold() const { return static_cast<int>(getArticles(true).size()); }
+
+int Seller::numArticlesOffered() const { return numArticlesOffered_; }
+
+//int Seller::numArticlesTotal() const { return static_cast<int>(getArticles().size()); }
\ No newline at end of file
diff --git a/src/core/seller.h b/src/core/seller.h
index a713292..c5f3e4a 100644
--- a/src/core/seller.h
+++ b/src/core/seller.h
@@ -15,24 +15,25 @@ class Seller : public Entity
   public:
     Seller();
     Seller(const std::string& firstName, const std::string& lastName, int sellerNo = 0,
-           int numberOfArticles = 0);
+           int numArticlesOffered = 0);
 
     void setSellerNo(int sellerNo);
     void setFirstName(const std::string& firstName);
     void setLastName(const std::string& lastName);
-    void setNumberOfOfferedArticles(int number);
+    void setNumArticlesOffered(int number);
     void addArticle(std::shared_ptr<Article> article);
 
     std::string getFirstName() const;
     std::string getLastName() const;
     int getSellerNo() const;
-    int getNumberOfOfferedArticles() const;
-    size_t soldArticles() const;
-    std::vector<Article*> getArticles(bool onlySold = false) const;
+    int numArticlesOffered() const;
+    int numArticlesSold() const;
+    //int numArticlesTotal() const;
+    std::vector<Article*> getArticles(bool onlySold = true) const;
 
   private:
     int sellerNo_{-1};
-    int numberOfOfferedArticles_{};
+    int numArticlesOffered_{};
     std::string firstName_{};
     std::string lastName_{};
     std::vector<std::shared_ptr<Article>> articles_{};
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 382580f..a6f7d20 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -11,3 +11,7 @@ add_test(NAME Article COMMAND ${CMAKE_BINARY_DIR}/bin/test_article)
 add_executable(test_database test_database.cpp)
 target_link_libraries(test_database core Boost::unit_test_framework stdc++fs)
 add_test(NAME Database COMMAND ${CMAKE_BINARY_DIR}/bin/test_database)
+
+add_executable(test_sale test_sale.cpp)
+target_link_libraries(test_sale core Boost::unit_test_framework)
+add_test(NAME Sale COMMAND ${CMAKE_BINARY_DIR}/bin/test_sale)
diff --git a/test/test_sale.cpp b/test/test_sale.cpp
new file mode 100644
index 0000000..0ee1bed
--- /dev/null
+++ b/test/test_sale.cpp
@@ -0,0 +1,33 @@
+#define BOOST_TEST_MODULE sale
+
+#include "../src/core/sale.h"
+
+#include <vector>
+
+#include <boost/test/included/unit_test.hpp>
+
+
+BOOST_AUTO_TEST_CASE(articles_sum)
+{
+    const int NUM_ARTICLES = 30;
+
+    Seller seller("Max", "Mustermann", 1, NUM_ARTICLES);
+    std::vector<std::shared_ptr<Article>> articles{};
+    Sale sale{};
+
+    for(int i = 0; i < NUM_ARTICLES; ++i)
+    {
+        auto art = std::make_shared<Article>();
+        art->setPrice((i+1) * 10);
+        articles.push_back(art);
+        seller.addArticle(art);
+    }
+
+    for(int i = 0; i < 10; ++i)
+    {
+        sale.addArticle(articles.at(i));
+    }
+
+    BOOST_TEST(sale.sumInCents() == 550);
+    BOOST_TEST(seller.getArticles(true).size() == 10);
+}
\ No newline at end of file
diff --git a/test/test_seller.cpp b/test/test_seller.cpp
index 2c0468f..7708701 100644
--- a/test/test_seller.cpp
+++ b/test/test_seller.cpp
@@ -34,6 +34,6 @@ BOOST_AUTO_TEST_CASE(with_article) {
     auto article = std::make_shared<Article>();
     article->setDescription("Test article");
     seller.addArticle(article);
-    BOOST_TEST(seller.getArticles().at(0)->getDescription() == "Test article");
-    BOOST_TEST(seller.soldArticles() == 0);
+    BOOST_TEST(seller.getArticles(false).at(0)->getDescription() == "Test article");
+    BOOST_TEST(seller.numArticlesSold() == 0);
 }
\ No newline at end of file