@article{10_4064_am_19_1_135_138,
     author = {A. Olejniczak},
     title = {Note on the first order orthogonal projections},
     journal = {Applicationes Mathematicae},
     pages = {135--138},
     publisher = {mathdoc},
     volume = {19},
     number = {1},
     year = {1987},
     doi = {10.4064/am-19-1-135-138},
     zbl = {0647.41007},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/am-19-1-135-138/}
}