JapanKnowledge has added another 10 titles to their Shinpen Nihon koten bungaku zenshū 新編 日本古典文学全集 digital collection. The new titles are:
中古
今昔物語集 Konjaku monogatarishū
将門記 Shōmon ki
陸奥話記 Mutsu waki
中世
保元物語 Hōgen monogatari
平治物語 Heiji monogatari
宇治拾遺物語 Uji shūi monogatari
曾我物語 Soga monogatari
太平記 Taiheiki
義経記 Gikeiki
近世
仮名草子集 Kana-zōshishū
To access the SNKBZ e-collection, you must sign into JapanKnowledge. A tutorial is available here on how to search within the e-books.