Grigorio, Mircea. <br/><br/>
Nonstationary models of seismic ground acceleration / by Mi-rcea Grigorio, Sonia E. Ruiz and Emilio Rosenblueth. 

 - Buffalo, New York : National Center for Earthquake Engineering Research. 
 - 38 p. 
 - Technical report NCEER; 88-0043. .