Imaginary tale : 
Nahin, Paul J. 
 - Princeton, N.J. :  Princeton University Press,  1998 
 - xvi, 257 p. :  ill. ;  24 cm. 
<br/><br/> On t.p. [the square root of minus one]" appears as a radical over "-1"." 
<br/><br/><label>ISBN: </label>9780691146003 (acid-free paper | 0691027951 (cloth : alk. paper)