DNA packing in the filamentous viruses fd, Xf, Pfl and Pf3

Abstract
Spectral data for filamentous viruses in the presence and absence of Ag+, together with other parameters, indicate that the DNA structures in two of the viruses, fd and Xf, are similar to each other but that these differ from two quite unusual and different DNA structures in Pf1 and Pf3.