Analysis of information sources in references of the Wikipedia article "Siyer" in Turkish language version.
ʿAbd al-ʿAzīz al-Dūrī, Historical Writing, p.36: "Ahmad ibn Hanbal rejected the hadiths reported by Ibn Ishaq precisely on the grounds of their use of the collective isnād: "I see him relating a single hadith on the authority of a group of people, without distinguishing the words of one from those of another"" (Tanbih 9-43) But Ibn Hanbal did accept Ibn Ishaq's authority for the maghazi.
