Ba-merkazim u-va-tefutsot bi-teḳufat ha-Geʾonim : peraḳim be-toldot ha-geʾonut ṿe-rashut ha-golah be-Erets Yiśraʾel u-ve-Vavel ṿe-toldot ḥakhamim be-Mitsrayim u-ve-Afriḳah ha-tsefonit ; meyusadim ʿal kitve yad ha-genizah - Abramson, Shraga (Mossad Harav Kook, 1965)