Adolf, Leonard Allen,  1927- <br/><br/>
The Operation of the English navigation system in colonial Pennsylvania 1681-1750  a case study /  [microform] : 
by Leonard Allen Adolf. 
 - Ann Arbor, Mich. :  University Microfilms International,  1953. 
 - 1 microfilm reel :  positive ;  35 mm. 
<br/><br/>Thesis (Ph.D.) - University of Washington, 1953. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Merchant marine--History--17th century.--United Kingdom<br/>Merchant marine--History--18th century.--United Kingdom<br/>Merchant marine--History--17th century.--United States<br/>Merchant marine--History--18th century.--United States