diff --git a/YACOSCore/ejbModule/org/yacos/core/conferences/Conference.java b/YACOSCore/ejbModule/org/yacos/core/conferences/Conference.java
index e6ca4be..6c953e1 100644
--- a/YACOSCore/ejbModule/org/yacos/core/conferences/Conference.java
+++ b/YACOSCore/ejbModule/org/yacos/core/conferences/Conference.java
@@ -2,22 +2,19 @@ package org.yacos.core.conferences;
 
 import java.io.Serializable;
 import java.util.ArrayList;
-import java.util.Collection;
 import java.util.Date;
+import java.util.List;
 
 import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
 import javax.persistence.Id;
-import javax.persistence.JoinColumn;
 import javax.persistence.OneToMany;
-import javax.persistence.OneToOne;
 import javax.persistence.Temporal;
 import javax.persistence.TemporalType;
 
 import org.yacos.core.article.Article;
 import org.yacos.core.users.Role;
-import org.yacos.core.users.User;
 
 
 @Entity
@@ -46,14 +43,14 @@ public class Conference implements Serializable{
 	 * Roles of users for this conference 
 	 */
 	@OneToMany(targetEntity=Role.class,mappedBy="conference")
-	private Collection<Role> roles;
+	private List<Role> roles;
 	
 /*	@OneToOne(targetEntity=User.class,optional=true)
 	@JoinColumn(name="chairman_id",nullable=true)
 	private User chairman;
 */	
 	@OneToMany(targetEntity=Article.class,mappedBy="conference")
-	private Collection<Article> articles;
+	private List<Article> articles;
 /*
 	/**
 	 * @return the chairman
@@ -158,22 +155,22 @@ public class Conference implements Serializable{
 	}
 
 	@OneToMany(targetEntity=Article.class,mappedBy="articles")
-	public void setArticles(Collection<Article> articles) {
+	public void setArticles(List<Article> articles) {
 		this.articles = articles;
 	}
 	
 	@OneToMany(targetEntity=Article.class,mappedBy="articles")
-	public Collection<Article> getArticles() {
+	public List<Article> getArticles() {
 		return articles;
 	}
 
 	@OneToMany(targetEntity=Role.class,mappedBy="conference")
-	public Collection<Role> getRoles() {
+	public List<Role> getRoles() {
 		return roles;
 	}
 
 	@OneToMany(targetEntity=Role.class,mappedBy="conference")
-	public void setRoles(Collection<Role> roles) {
+	public void setRoles(List<Role> roles) {
 		this.roles = roles;
 	}
 }
diff --git a/YACOSCore/ejbModule/org/yacos/core/conferences/ConferenceManagerBean.java b/YACOSCore/ejbModule/org/yacos/core/conferences/ConferenceManagerBean.java
index 9450ee9..226a2ab 100644
--- a/YACOSCore/ejbModule/org/yacos/core/conferences/ConferenceManagerBean.java
+++ b/YACOSCore/ejbModule/org/yacos/core/conferences/ConferenceManagerBean.java
@@ -42,7 +42,7 @@ public class ConferenceManagerBean implements IConferenceManager {
 		em.merge(conf);
 	}
 
-	public Collection<Article> getArticles(Integer conference_id) {
+	public List<Article> getArticles(Integer conference_id) {
 		//FIXME cast a verifier lors des tests
 		return getConference(conference_id).getArticles();
 	}
diff --git a/YACOSCore/ejbModule/org/yacos/core/conferences/IConferenceManager.java b/YACOSCore/ejbModule/org/yacos/core/conferences/IConferenceManager.java
index 5adbc22..8354d53 100644
--- a/YACOSCore/ejbModule/org/yacos/core/conferences/IConferenceManager.java
+++ b/YACOSCore/ejbModule/org/yacos/core/conferences/IConferenceManager.java
@@ -16,7 +16,7 @@ public interface IConferenceManager {
 	//CRUD methodes
 	public Conference addConference(String titre, String descirption, String infoComplementray, Date dataAbstract, Date dateArticle, Date dateEvaluation, Date dateStart, Date dateEnd);
 	public Conference getConference(Integer id);
-	public Collection<Conference> getConferences();
+	public List<Conference> getConferences();
 	public void remove(Conference conf);
 	public void update(Conference conf);