Qadi Numan is a prolific author and Jurist credited with 45+ works. Qadi Nu'man served under 4 Fatimid Caliphs. His Biography and work is presented in this early article by Asaf Ali Ashgar Fyzee, the expert in the field of study of Qadi Numan's work.
Also other sources are available for Qadi Numan's life and work:
http://ismaili.net/heritage/node/9632
http://ismaili.net/heritage/node/10690
http://ismaili.net/heritage/node/6951
The PDF file of the article is available for download in the link below.