@article {IOPORT.06082062,
    author       = {Binkele-Raible, Daniel and Fernau, Henning},
    title        = {An exact exponential-time algorithm for the directed maximum leaf spanning tree problem.},
    year         = {2012},
    journal      = {Journal of Discrete Algorithms},
    volume       = {15},
    issn         = {1570-8667},
    pages        = {43-55},
    publisher    = {Elsevier Science B.V., Amsterdam},
    doi          = {10.1016/j.jda.2012.03.006},
    abstract     = {Summary: Given a directed graph $G=(V,A)$, the directed maximum leaf spanning tree problem asks to compute a directed spanning tree with as many leaves as possible. By designing a branching algorithm analyzed with Measure\&Conquer, we show that the problem can be solved in time $\cal O^{\ast}(1.9044^{n})$ using polynomial space. Allowing exponential space, this run time upper bound can be lowered to $\cal O^{\ast}(1.8139^{n})$. We also provide an example showing a lower-bound for the running time of our algorithm.},
    identifier   = {06082062},
}