@article{SMJ2_2013_39_2_a4,
     author = {Krastev, Vladimir},
     title = {Mangasarian-type {Sufficient} {Optimality} {Conditions} for {Age-Structured} {Control} {Problems} with {State} {Constraints.} {An} {Application} to {Investment} in {Vintage} {Capital}},
     journal = {Serdica Mathematical Journal},
     pages = {155--188},
     publisher = {mathdoc},
     volume = {39},
     number = {2},
     year = {2013},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SMJ2_2013_39_2_a4/}
}