@manual{wb_spec,
    title = {Wishbone bus specification (rev.B4)},
      organization = {OpenCores/OrSOC}
}

@manual{pll_base,
    title = {Spartan-6 FPGA Clocking Resources, User Guide},
    organization = {Xilinx}
}

@manual{wrpc_man,
    title = {White Rabbit PTP Core User's Manual - Building and Running 
      (\url{http://www.ohwr.org/attachments/download/1586/wrpc-v2.0.pdf})},
    author = {Grzegorz Daniluk}
}
