Blyton , Enid <br/><br/>
The mystery secret room :  

 - Dean:   London ;   1943. 
 - 216 p  ; 21 cm .  01 
 - 2025-06-04 
<br/><br/><label>ISBN: </label>9780603567001 
<br/><br/><label>Nat. Bib. No.: </label>0011302 
<br/><br/><label>Nat. Bib. Agency Control No.: </label>BLY 
<br/><br/><label>Universal Decimal Class. No.: </label>823