Ehrman, Madeline Elizabeth. <br/><br/>
The meaning of the modals in present-day American English. 

 - The Hague :  Mouton,  1966. 
 - Janua linguarum. Series practica ;  Janua linguarum. Series practica ;  45 .
<br/><br/>Bibliography: p. [104]-106. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>English language -- United States -- Verb.--English language -- United States -- Verb.--English language -- United States -- Verb.<br/>English language -- United States -- Mood.--English language -- United States -- Mood.--English language -- United States -- Mood.