Keene, Carolyn. <br/><br/>
The message in the hollow oak / 
Carolyn Keene. 
 - New York :  Grosset & Dunlap,  1975, c1935 
 - 181 p. 
<br/><br/> Nancy Drew tackles a mystery professional detectives failed to solve--finding a valuable centuries-old message in a hollow oak tree in Illinois. 
<br/><br/><label>ISBN: </label>0448095122 0448095127 
<br/><br/><label>Index Terms--Genre/Form: </label><br/>Detective and mystery stories.
<br/><br/><label>LC Class. No.: </label>PZ7.K23  / Nan no. 12 1972