Examples of type I duplicates (duplicates among databases).
– All examples originated from the literatures regarding portal vein thrombosis.
– In every example, the same study was simultaneously recorded by two or three databases.
– All literatures were expressed in Vancouver reference type.
– Bold and italics formatting indicated the different styles between index and redundant paper(s).
– In every example, the reference recorded by PubMed database had more complete information.