@article{JRAM_1986__368_152839,
     author = {Ziv Ran},
     title = {Surfaces of order 1 in {Grassmannians.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {119--126},
     publisher = {mathdoc},
     volume = {368},
     year = {1986},
     zbl = {0601.14042},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1986__368_152839/}
}