@article{JRAM_1975__0278_0279_151645,
     author = {Margret H\"oft},
     title = {The order-sum in classes of partially ordered algebras.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {78--92},
     publisher = {mathdoc},
     volume = {0278_0279},
     year = {1975},
     zbl = {0325.08002},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1975__0278_0279_151645/}
}