Obtaining More Answers from Information Integration Systems. - Gösta Grahne; Victoria Kiricenko (WebDB, 2002)

Partial answers in information integration systems. - Gösta Grahne; Victoria Kiricenko (WIDM, 2003)

Towards an algebraic theory of information integration. - Gösta Grahne; Victoria Kiricenko (Inf. Comput., 2004)