* [[C. E. BoshworthBosworth]], ''[http://histories.cambridge.org/extract?id=chol9780521200936_CHOL9780521200936A004 Cambridge History of Iran]'', volum IV, {{pdf}} en línia (previ pagament o subscripció)
* [[C. E. BoshworthBosworth]], ''[http://books.google.cat/books?id=mKpz_2CkoWEC&pg=PA172&hl=ca&source=gbs_toc_r&cad=3#v=onepage&q&f=false The New Islamic dynasties]'', [http://books.google.cat/books?id=hvx9jq_2L3EC&pg=PR13&lpg=PR13&dq=cambridge+history+of+iran+volume+4&source=bl&ots=FbDWSPz3Ex&sig=FQr4gAnc_HBM0uObKbcDWknVh1w&hl=ca&sa=X&ei=_wMoT4h1kJY6s5bJxQI&ved=0CGIQ6AEwBg#v=onepage&q=cambridge%20history%20of%20iran%20volume%204&f=false parcialment] Edimburg 1996
* Theodor Nöldeke, ''Yakub der Kupferschmied und seine Dynastie, a Orientalische Skizzen'', Berlín 1892, traducció a l'anglès a ''Sketches from oriental history'', Londres i Edimburg, 1892.
* [[C. E. BoshworthBosworth]], ''Sistan under the Arab from the Islamic conquest to the rise of Saffarids (30-250/651-864)'', Roma 1968
* [[C. E. BoshworthBosworth]], ''The history of the Daffarids if Sistan and the Maliks of Nimruz (247-861 to 949/1542-3)'', Costa Mesa i Nova York, 1994.
* [[C. E. BoshworthBosworth]], [http://www.iranicaonline.org/articles/yaqub-b-lay-b-moaddal "YAʿQUB b. LAYṮ b. MOʿADDAL"] a [[Encyclopaedia Iranica]]
