@article{10_4064_ba55_1_1,
     author = {Arthur W. Apter and Grigor Sargsyan},
     title = {A {Reduction} in {Consistency} {Strength
for} {Universal} {Indestructibility}},
     journal = {Bulletin of the Polish Academy of Sciences. Mathematics},
     pages = {1--6},
     publisher = {mathdoc},
     volume = {55},
     number = {1},
     year = {2007},
     doi = {10.4064/ba55-1-1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ba55-1-1/}
}