some links cannot back Sage Reference Manual
1 https://sage.epsevg.upc.edu:8000/doc/...
when link below,no button to back to Sage Reference Manual
REFERENCES:
[WpJacobianVariety] http://en.wikipedia.org/wiki/Jacobian...
2
https://sage.epsevg.upc.edu:8000/doc/...
when link below,no button to back to Sage Reference Manual,it link to http://trac.sagemath.org/13100,but blank page...
there are more links like above troubles at other places in Sage Reference Manual,I meet several times