MARC Bibliographic records can be loaded using these tools:

• Stage MARC Recorcd for import
  • Documentation: http://manual.koha-community.org/3.6/en/stagemarc.html 
• Staged MARC Record management
  • Documentation: http://manual.koha-community.org/3.6/en/managestaged.html

Click the Tools button on the Koha Staff main page, or select Tools from the More drop-down menu. Stage Marc Records for Import is in the middle column.

Once a file is staged, you can find matching records, import, and un-import the file. For the record matching rules, click the  Koha Administration button on the Koha Staff main page, or select Adminstration from the More drop-down menu. Record Matching Rules is towards the end of the Catalog section.