@article{10_4064_fm175_2_3,
     author = {Alex Hellsten and Tapani Hyttinen and Saharon Shelah},
     title = {Potential isomorphism and semi-proper trees},
     journal = {Fundamenta Mathematicae},
     pages = {127--142},
     publisher = {mathdoc},
     volume = {175},
     number = {2},
     year = {2002},
     doi = {10.4064/fm175-2-3},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm175-2-3/}
}