@article{1178240942,
author = {Sekigawa, Kouei},
title = {On some $3$-dimensional complete Riemannian manifolds satisfying $R(X,\,Y)\cdot R=0$},
journal = {Tohoku Math. J. (2)},
volume = {27},
number = {4},
year = {1975},
pages = { 561-568},
language = {en},
url = {http://dml.mathdoc.fr/item/1178240942}
}
Sekigawa, Kouei. On some $3$-dimensional complete Riemannian manifolds satisfying $R(X,\,Y)\cdot R=0$. Tohoku Math. J. (2), Tome 27 (1975) no. 4, pp. 561-568. http://gdmltest.u-ga.fr/item/1178240942/