@article{10_4064_fm_89_2_155_171,
     author = {David Kueker},
     title = {Core structures for theories},
     journal = {Fundamenta Mathematicae},
     pages = {155--171},
     publisher = {mathdoc},
     volume = {89},
     number = {2},
     year = {1975},
     doi = {10.4064/fm-89-2-155-171},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-89-2-155-171/}
}