Untested: 
for my $k (sort keys %ManagerInCharge){
    print "Month: $k\n";
    my @keys = keys %{$ManagerInCharge{$k}};
    print "Managers: ", join(",", @keys), "\n";
}

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In reply to Re: Extracting a list of keys from a multi-dimensional hash. by moritz
in thread Extracting a list of keys from a multi-dimensional hash. by PerlKitten

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