I believe this should work, XML::Simple all hinges on nested hash & array references. 
my $sources = $ref->{'sas_residue_annotation'}->{'sources'};
foreach my $s (@{ $sources }) {
  print $s->{'source_name'}->[0], "\n";
}

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just another cpan module author

In reply to Re: request for help on working with XML::Simple by spatterson
in thread request for help on working with XML::Simple by Angharad

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