CD-ROM is now generally considered to be a transitional technology, nevertheless, the number of installed drives continues to grow. By the end of 1996, more than 100 million CD-ROM drives were installed worldwide. Applications software is commonly distributed in this format, and the number of electronic publications on CD-ROM grows by more than 25 percent per year. We expect that the format will last at least another five years, but that eventually CD-ROM will be replaced by higher capacity media for electronic publications requiring several Gigabytes of storage, and also by online reference services available via the Internet.