There is no documentation download on http://monkey.org/~provos/libevent/ and its sourceforge project web site. To generate libevent documentation by yourself, follow the following steps.
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git clone git://levent.git.sourceforge.net/gitroot/levent/levent
./autogen.sh
./configure
./make doxygen
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The you can find libevent html documentation in doxygen directory.
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