1. Anderson, E.S.: The ecology of the transferable drug resistance in the enterobacteria. Ann. Rev. Microbiol. 22, 131 (1968).
2. Bauer, W. and J. Vinograd: The interaction of closed circular DNA with intercalative dyes. I. The superhelix density of SV40 DNA in the presence and absence of dye. J. Mol. Biol. 33, 141. (1968).
3. Bauer, W. and J. Vinograd: The use of intercalative dyes in the study of closed circular DNA. In Progr. Mol. Subcell. Biol. 2, 181 (1971). F.E. Hahn edt. Springer, Berlin-Heidelberg-New York.
4. Bazaral, M. and D.R. Helinski: Circular form of colicinogenic factors El, E2 and E3 from Escherichia coli. J. Mol. Biol. 36, 185 (1968).
5. Borst, P.: Mitochondrial nucleic acids. Ann. Rev. Biochem. 41, 333 (1972).