Visualforce page apex:outputField for Custom Lookup display value and label

Visualforce Page :

 <apex:pageBlockSectionItem >

                  <apex:outputLabel >Good Recive Note</apex:outputLabel>

                   <apex:panelGroup layout="block" styleClass="requiredInput">

                    <apex:panelGroup layout="block" styleClass="requiredBlock" />

                   <apex:outputfield value="{!Goods_Received_Note__c.Purchase_Order__c}" id="ddlPO"   />

                   </apex:panelGroup>          

                         </apex:pageBlockSectionItem>

Custom Button :

{!REQUIRESCRIPT("/soap/ajax/22.0/connection.js")}

{!REQUIRESCRIPT("/soap/ajax/22.0/apex.js")}

var query = "Select Id, Purchase_Order__c, Receive_All_Qty__c from Purchase_Order_Line_Item__c  Where Purchase_Order__c= '{!Purchase_Order__c.Id}' And Receive_All_Qty__c = false LIMIT 1";

var result = sforce.connection.query(query);

var arrayResult = result.getArray('records');

if (arrayResult.length == 0)

{

alert('There are no products for dispatch');

}

else

{

window.location.href='/apex/CreateGoodRecivefromPO?CF00N20000009EtQI={!Purchase_Order__c.Name}&CF00N20000009EtQI_lkid={!Purchase_Order__c.Id}&scontrolCaching=1&sfdc.override=1&retURL={!Purchase_Order__c.Id}';

}