The bibliography aims at providing a complete list of all scholarly articles that are relevant to the description of species among the Macrostomorpha. Where possible each citation has an attached PDF file.
This file was scanned to PDF (generally from an already copied original) using a copy machine with an built-in document scanner. The resulting file was optimized using the default settings of the 'Optimize Scanned PDF' function of Adobe Acrobat Professional and then converted into searchable text with the built-in 'OCR Text Recognition' function. Whenever possible the appropriate primary OCR language was used and the 'Searchable Image (Exact)' output option without downsampling was selected.
This yields a document in which the recognized text is searchable, but the file still displays the scanned image. This is important, because the quality of the optical character recognition is variable and strongly depends on the quality of the original copy. If you think you have higher quality copy of a given article, please consider donating it to the site.
Finally, you should be careful in concluding that a certain word does not occur in a document if you can't find it in the document. The human eye is still much better at making sense of a low-quality scans than a computer.