Create shortcode to display attached file type

If say I have multiple files attached in a loop, but I want to display only the PDF document that is attached, and not other documents that are also attached, how would I only display the file type (pdf) that I want?

My current loop looks like this below. That’s where I want the loop only to display the attached PDF and not all the rest of the documents with it:

[loop type=newsletter paged=1 taxonomy=newsletter_categories term=statistics]

  [repeater newsletter_attachments]
     [attached field=newsletter_document]
        <h4>[field title-link]</h4>
     [/attached]
  [/repeater]

[/loop]