diff --git a/dnet-ariadneplus-graphdb-publisher/test/java/eu/dnetlib/ariadneplus/elasticsearch/BulkUploadTest.java b/dnet-ariadneplus-graphdb-publisher/test/java/eu/dnetlib/ariadneplus/elasticsearch/BulkUploadTest.java
index 6f9fafb..1384721 100644
--- a/dnet-ariadneplus-graphdb-publisher/test/java/eu/dnetlib/ariadneplus/elasticsearch/BulkUploadTest.java
+++ b/dnet-ariadneplus-graphdb-publisher/test/java/eu/dnetlib/ariadneplus/elasticsearch/BulkUploadTest.java
@@ -5,7 +5,13 @@ import org.junit.Before;
 import org.junit.Test;
 
 public class BulkUploadTest {
-
+ /*
+ About BoundingBox and WKT:
+ X = LONGITUDE; Y = LATITUDE
+bbox2wkt(minx = NA, miny = NA, maxx = NA, maxy = NA, bbox = NULL)
+bbox:   MIN LONG, MIN LAT,MAX LONG, MAX LAT
+wkt <- "POLYGON((MINLONG MINLAT,MINLONG MAXLAT,MAXLON MAXLAT,MAXLON MINLAT,MINLON MINLAT))"
+  */
     private BulkUpload bu;
 
     @Before
@@ -55,5 +61,4 @@ public class BulkUploadTest {
         System.out.println("Long: "+centroid.getLon()+", Lat: "+centroid.getLat());
     }
 
-
 }