open(FILEHANDLE, "steve_list_plaintext.txt");
while(<FILEHANDLE>) {
    @words = split(/ /, $_);
    while($words[0] =~ /^[A-Z]\./) { shift @words; }
    chomp $words[0];
    $fields{$words[0]}++;
}
close(FILEHANDLE);

open(FILE2, "di_list_plaintext.txt");
while(<FILE2>) {
    @words = split(/ /, $_);
    while($words[0] =~ /^[A-Z]\./) { shift @words; }
    chomp $words[0];
    if($fields{$words[0]} > 0) { print "$_"; }
}