1. Unpublished or unpublished books may be manuscripts never completed by the author or unpublished books by the publishing house.
Illegally published books, which are usually unauthorized publications and published by various individuals or organizations.
Third, non-commercial publications, such as books published by the government, research institutions or schools, generally do not appear in bookstores.
Fourth, collecting books, usually ancient books, has high collection value and is difficult to find in bookstores.
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