Bybee, J. <br/><br/>
The evolution of grammar:  tense, aspect, and modality in the languages of the world/ 

 - Chicago:  University of Chicago,  1994. 
 - ix, 398 p.:  ill,;  23 cm. 
<br/><br/> includes an bibliography,  references and index  
<br/><br/><label>ISBN: </label>9780226086651 
<br/><br/><label>LC Class. No.: </label>DUCE P299.G.73B93