Page 106 - JOURNAL OF LIBRARY SCIENCE IN CHINA 2015 Vol. 41

Xincai WANG, Haining WANG / Empirical study on journal literature guarantee of academic library: A case study of Wuhan University 105

the redundancy among databases, the unavailable-title curve of E∪P∪OA runs in the bottom of
Figure 5.

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& 1 0" &6160"
Figure 4. Unavailability percentage of cited references caused by unavailable issues.

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Figure 5. Unavailability percentage of cited references caused by unavailable titles.

To some extent, the tendency of electronic unavailable-issue curve shown in Figure 4 reflects
the difference between the two causes of electronic resource access failure mentioned before. Since
2002, the unavailable-issue percentage of full-text databases is below 10%. According to the last
ten-year annual data (2004-2013) of the electronic unavailable-issue curve (ranging from 5.86%
to 9.56%), current issue databases have a quality defect in collection continuity commonly. This