A quick and dirty fudge would be :-

my $data='';

while (<>) {
    my $line=$_;
    $line=~s/[\n\r\l]//g;
    if (length($line)<10) {
        $data.=$line;
    } else {
        if ($data=~m/(?:\s[12]\d{3}\s*\)|\spp.\s+)/) {
        print "$data\n\n";
        $data=$line;
    } else {
            $data.=$line;
        }
    }    
}
print "$data\n\n";
[download]

Looks like that catches the other cases
UnderMine

update: added last print to catch final entry