S. Reza Hejazi Azizollah Memariani Gholam Reza Jahanshahloo Mohammad Mehdi Sepehri Linear bilevel programming solution by genetic algorithm. 1913-1925 2002 29 Computers & OR 13 http://dx.doi.org/10.1016/S0305-0548(01)00066-1 db/journals/cor/cor29.html#HejaziMJS02