This encyclopedia is primarily based on the scientific and English names defined in IOC World Bird List (rev. 7.3)
The Clements Checklist of Birds of the World (in short: Clements Checklist) is another major source in my work with this encyclopedia.
Notice: Other bird lists, books and sources may use different classifications and names.
Whenever there is dispute about classification or the official English name, I will mention it in the articles. I will also add all known synonyms in the indexes in order to make it easier to search for specific species where there may be dispute about the proper scientific or English name.