diff --git a/lib/Constants.php b/lib/Constants.php
index eb4dd329..90ec6777 100644
--- a/lib/Constants.php
+++ b/lib/Constants.php
@@ -27,7 +27,6 @@ const SOURCE_HATHI_TRUST = 1;
 const SOURCE_WIKISOURCE = 2;
 const SOURCE_INTERNET_ARCHIVE = 3;
 const SOURCE_GOOGLE_BOOKS = 4;
-const SOURCE_DP_OLS = 5;
 const SOURCE_OTHER = 6;
 const SOURCE_PROJECT_GUTENBERG_CANADA = 7;
 const SOURCE_PROJECT_GUTENBERG_AUSTRALIA = 8;
diff --git a/lib/Ebook.php b/lib/Ebook.php
index dd7ce742..dd0fb2e9 100644
--- a/lib/Ebook.php
+++ b/lib/Ebook.php
@@ -410,9 +410,6 @@ class Ebook{
 			elseif(mb_stripos($e, 'books.google.com/') !== false || mb_stripos($e, 'google.com/books/') !== false){
 				$this->Sources[] = new EbookSource(SOURCE_GOOGLE_BOOKS, $e);
 			}
-			elseif(mb_stripos($e, 'www.pgdp.org/ols/') !== false){
-				$this->Sources[] = new EbookSource(SOURCE_DP_OLS, $e);
-			}
 			elseif(mb_stripos($e, 'www.fadedpage.com') !== false){
 				$this->Sources[] = new EbookSource(SOURCE_FADED_PAGE, $e);
 			}
diff --git a/www/ebooks/ebook.php b/www/ebooks/ebook.php
index 4ee60abd..662f0933 100644
--- a/www/ebooks/ebook.php
+++ b/www/ebooks/ebook.php
@@ -281,7 +281,6 @@ catch(\Exception $ex){
 						<? if($source->Type == SOURCE_INTERNET_ARCHIVE){ ?><a href="<?= Formatter::ToPlainText($source->Url) ?>" class="internet-archive">Page scans at the Internet Archive</a><? } ?>
 						<? if($source->Type == SOURCE_HATHI_TRUST){ ?><a href="<?= Formatter::ToPlainText($source->Url) ?>" class="hathitrust">Page scans at HathiTrust</a><? } ?>
 						<? if($source->Type == SOURCE_GOOGLE_BOOKS){ ?><a href="<?= Formatter::ToPlainText($source->Url) ?>" class="google">Page scans at Google Books</a><? } ?>
-						<? if($source->Type == SOURCE_DP_OLS){ ?><a href="<?= Formatter::ToPlainText($source->Url) ?>" class="distributed-proofreaders">Page scans at Distributed Proofreaders Open Library System</a><? } ?>
 						<? if($source->Type == SOURCE_FADED_PAGE){ ?><a href="<?= Formatter::ToPlainText($source->Url) ?>" class="globe">Transcription at Faded Page</a><? } ?>
 						<? if($source->Type == SOURCE_OTHER){ ?><a href="<?= Formatter::ToPlainText($source->Url) ?>" class="globe"><?= Formatter::ToPlainText(preg_replace(['|https?://(en\.)?|', '|/.+$|'], '', (string)$source->Url) ?? '') /* force type to (string) to satisfy PHPStan */ ?></a><? } ?>
 					</p>