@article {Bertola:Warped, title = {Warped products with special Riemannian curvature}, journal = {Bol. Soc. Brasil. Mat. (N.S.)}, volume = {32}, number = {1}, year = {2001}, pages = {45{\textendash}62}, issn = {0100-3569}, author = {Marco Bertola and Gouthier, Daniele} }