@article{10_21136_MB_2003_133931,
     author = {Kim, Young Hee and Kim, Hee Sik},
     title = {Subtraction algebras and $BCK$-algebras},
     journal = {Mathematica Bohemica},
     pages = {21--24},
     publisher = {mathdoc},
     volume = {128},
     number = {1},
     year = {2003},
     doi = {10.21136/MB.2003.133931},
     mrnumber = {1973421},
     zbl = {1014.06018},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/MB.2003.133931/}
}