diff --git a/homeworks/02-goodreads/README.md b/homeworks/02-goodreads/README.md
index f49523df..533d7da8 100644
--- a/homeworks/02-goodreads/README.md
+++ b/homeworks/02-goodreads/README.md
@@ -41,22 +41,22 @@
 
 ```java
 package bg.sofia.uni.fmi.mjt.goodreads.recommender;
- 
+
 import bg.sofia.uni.fmi.mjt.goodreads.book.Book;
- 
-import java.util.Map;
- 
+
+import java.util.SortedMap;
+
 public interface BookRecommenderAPI {
 
     /**
      * Searches for books that are similar to the provided one.
      *
-     * @param  originBook the book we should calculate similarity with.
-     * @param  maxN - the maximum number of entries returned
-     * @throws IllegalArgumentException if the originBook is null.       
-     * @throws IllegalArgumentException if maxN is smaller than or equal to 0.                             
-     * @return a Map<Book, Double> representing the top maxN closest books with their similarity to originBook
-     * ordered by their similarity score in descending order
+     * @param originBook the book we should calculate similarity with.
+     * @param maxN       the maximum number of entries returned
+     * @return a SortedMap<Book, Double> representing the top maxN closest books
+     * with their similarity to originBook ordered by their similarity score
+     * @throws IllegalArgumentException if the originBook is null.
+     * @throws IllegalArgumentException if maxN is smaller or equal to 0.
      */
     SortedMap<Book, Double> recommendBooks(Book originBook, int maxN);
 
diff --git a/homeworks/02-goodreads/resources/src/bg/sofia/uni/fmi/mjt/goodreads/recommender/BookRecommender.java b/homeworks/02-goodreads/resources/src/bg/sofia/uni/fmi/mjt/goodreads/recommender/BookRecommender.java
index b69acf57..6ff54662 100644
--- a/homeworks/02-goodreads/resources/src/bg/sofia/uni/fmi/mjt/goodreads/recommender/BookRecommender.java
+++ b/homeworks/02-goodreads/resources/src/bg/sofia/uni/fmi/mjt/goodreads/recommender/BookRecommender.java
@@ -3,17 +3,18 @@
 import bg.sofia.uni.fmi.mjt.goodreads.book.Book;
 import bg.sofia.uni.fmi.mjt.goodreads.recommender.similaritycalculator.SimilarityCalculator;
 
-import java.util.Map;
 import java.util.Set;
+import java.util.SortedMap;
 
 public class BookRecommender implements BookRecommenderAPI {
 
-    public BookRecommender(Set<Book> initialBooks, SimilarityCalculator calculator) {}
-
+    public BookRecommender(Set<Book> initialBooks, SimilarityCalculator calculator) {
+        throw new UnsupportedOperationException("Not yet implemented");
+    }
 
     @Override
-    public Map<Book, Double> recommendBooks(Book origin, int maxN) {
+    public SortedMap<Book, Double> recommendBooks(Book origin, int maxN) {
         throw new UnsupportedOperationException("Not yet implemented");
     }
-    
+
 }
diff --git a/homeworks/02-goodreads/resources/src/bg/sofia/uni/fmi/mjt/goodreads/recommender/BookRecommenderAPI.java b/homeworks/02-goodreads/resources/src/bg/sofia/uni/fmi/mjt/goodreads/recommender/BookRecommenderAPI.java
index b30fb9b9..b9eaacb7 100644
--- a/homeworks/02-goodreads/resources/src/bg/sofia/uni/fmi/mjt/goodreads/recommender/BookRecommenderAPI.java
+++ b/homeworks/02-goodreads/resources/src/bg/sofia/uni/fmi/mjt/goodreads/recommender/BookRecommenderAPI.java
@@ -2,19 +2,20 @@
 
 import bg.sofia.uni.fmi.mjt.goodreads.book.Book;
 
-import java.util.Map;
+import java.util.SortedMap;
 
 public interface BookRecommenderAPI {
 
     /**
      * Searches for books that are similar to the provided one.
      *
-     * @param  originBook the book we should calculate similarity with.
-     * @param  maxN - the maximum number of entries returned
+     * @param originBook the book we should calculate similarity with.
+     * @param maxN       the maximum number of entries returned
+     * @return a SortedMap<Book, Double> representing the top maxN closest books
+     * with their similarity to originBook ordered by their similarity score
      * @throws IllegalArgumentException if the originBook is null.
      * @throws IllegalArgumentException if maxN is smaller or equal to 0.
-     * @return a Map<Book, Double> representing the top maxN closest books with their similarity to originBook ordered by their similarity score
      */
-    Map<Book, Double> recommendBooks(Book originBook, int maxN);
-    
+    SortedMap<Book, Double> recommendBooks(Book originBook, int maxN);
+
 }