Analyses of strong motion earthquake accelerograms : vol. 4- fourier amplitude spectra, part B : accelerograms IIB021 -througth IIB040 / California Institute of Technology. 

 - Pasadena, Calif. : Research Laboratory 
 - 131 p. 
 - [Report] ; EERL 73-100 / CALTEC, Earthquake Engineering Res-earch Laboratory .