@article{MR_1983_25_a3,
     author = {Anthony W. Hager and  James  J. Madden},
     title = {Algebraic {Classes} of {Abelian} {Torsion-Free} and {Lattice-Ordered} {Groups}},
     journal = {M\ensuremath{\alpha}\ensuremath{\theta}\ensuremath{\eta}\ensuremath{\mu}\ensuremath{\alpha}\ensuremath{\tau}\ensuremath{\iota}\ensuremath{\kappa}\ensuremath{\acute\eta} E\ensuremath{\pi}\ensuremath{\iota}\ensuremath{\theta}\ensuremath{\varepsilon}\ensuremath{\acute\omega}\ensuremath{\rho}\ensuremath{\eta}\ensuremath{\sigma}\ensuremath{\eta}},
     pages = {53--63},
     year = {1983},
     volume = {25},
     language = {gr},
     url = {http://geodesic.mathdoc.fr/item/MR_1983_25_a3/}
}