-Iterative methods used to solve large sparse linear systems of the form $Ax=b$
-because they are easier to parallelize than direct ones.
+Iterative methods are used to solve large sparse linear systems of equations of
+the form $Ax=b$ because they are easier to parallelize than direct ones. Many
+iterative methods have been proposed and adpated by many researchers. When
+solving large linear systems with many cores, iterative methods often suffer
+from scalability problems. This is due to their need for collective
+communications to perform matrix-vector products and reduction operations.
+
+\bibliographystyle{plain}
+\bibliography{biblio}