Complex sentence: The Vernadsky National Library of Ukraine's electronic catalog has a list of 23 publications, text books, monographs with Yanukovych listed as author, however, on further investigation the library does not have any copies of the above-mentioned works.
Split into simpler sentences: The Vernadsky National Library of Ukraine's electronic catalog has a list of 23 publications, text books, and monographs with Yanukovych listed as author. However, on further investigation the library does not have any copies of the above-mentioned works.