Blyton Enid <br/><br/>
Mystery of the spiteful letters: Being the fourth adventure of the five find-outers and dog 

 - London, UK  Methuen and Co. Ltd   1956 
 - vi,166p. 
<br/><br/><label>ISBN: </label>0 86311 430 X 
<br/><br/><label>Source: </label>Textual