@article{10_4064_fm_108_3_171_181,
     author = {Leo Marcus},
     title = {The number of countable models of a theory of one unary function},
     journal = {Fundamenta Mathematicae},
     pages = {171--181},
     publisher = {mathdoc},
     volume = {108},
     number = {3},
     year = {1980},
     doi = {10.4064/fm-108-3-171-181},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-108-3-171-181/}
}