This dictionary is out of copyright, and available for free online (as I suspect you know, but your readers might not), though the scanned PDF is not very high quality.
A high-quality electronic edition is currently in the works at Logos Bible Software. It contains extensive tagging and linking. For example, all cross-references are linked to the correct entry, and all references to the Hebrew Bible are also linked. The text is also fully searchable--you can search for any word in any language, even for words buried deep within any of the 30,000 entries.
Check it out here: Dictionary of the Targumim, the Talmud Babli and Yerushalmi, and the Midrashic Literature
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