Greenburg, Dan. <br/><br/>
Through the medicine cabinet / 
by Dan Greenburg. 
 - London :  McMillan Children's Books,  1988. 
 - 56 p. :  ill ;  20 cm. 
 - Zack files .
 - The Zack files .
<br/><br/> After Zack opens his medicine cabinet one morning and sees a boy who could be his double staring back at him, he enters a parallel universe. 
<br/><br/><label>ISBN: </label>0330353535 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Supernaturel--Fiction.