A comprehensive and up-to-date treatment of research carried out over the 1980s and 1990s on congruences involving the values of L-functions (attached to quadra... » 

A comprehensive and up-to-date treatment of research carried out over the 1980s and 1990s on congruences involving the values of L-functions (attached to quadratic characters) at certain special values. It presents in a unified way congruences found by many authors over the years. «