Update broken link in step-22 intro.dox

diff --git a/examples/step-22/doc/intro.dox b/examples/step-22/doc/intro.dox
index 0f9a9da7a8d9b71ba29bb2a8d34ba2ec4258f4e5..a11a1697e256b8f6cf9c7c6639fd94e69f0be438 100644 (file)
--- a/examples/step-22/doc/intro.dox
+++ b/examples/step-22/doc/intro.dox
@@ -464,7 +464,7 @@ we largely follow the paper D. Silvester and A. Wathen:
 "Fast iterative solution of stabilised Stokes systems part II. Using
 general block preconditioners." (SIAM J. Numer. Anal., 31 (1994),
 pp. 1352-1367), which is available online <a
-href="http://siamdl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=SJNAAM000031000005001352000001&idtype=cvips&gifs=Yes" target="_top">here</a>.
+href="https://doi.org/10.1137/0731070">here</a>.
 Principally, the difference in the matrix at the heart of the Schur
 complement has two consequences: