@article{BMMS_2006_29_2_a7,
     author = {Kenjiro Ogawa and Morimasa Tsuchiya},
     title = {Note on {Transformations} of {Posets} with the {Same} {Upper} {Bound} {Graph} and
      {Minimal} {Elements}},
     journal = {Bulletin of the Malaysian Mathematical Society},
     year = {2006},
     volume = {29},
     number = {2},
     url = {http://geodesic.mathdoc.fr/item/BMMS_2006_29_2_a7/}
}