\contentsline {section}{\tocsection {}{1}{Introduction}}{1}
\contentsline {section}{\tocsection {}{2}{Geometry}}{3}
\contentsline {section}{\tocsection {}{3}{Galois group - generic case}}{5}
\contentsline {section}{\tocsection {}{4}{Group cohomology}}{5}
\contentsline {section}{\tocsection {}{5}{Computation of ${\rm Br}(S)/{\rm Br}({\@mathbb Q})$ in the generic case}}{9}
\contentsline {section}{\tocsection {}{6}{The non-generic case}}{10}
\contentsline {section}{\tocsection {}{7}{Examples of Brauer-Manin obstruction}}{12}
\contentsline {section}{\tocsection {}{8}{Appendix: Cyclic Azumaya algebras on diagonal cubics}}{20}
\contentsline {section}{\tocsection {}{}{References}}{23}