http://en.wikipedia.org/wiki/Widlar_current_source

http://www.manchesteruniversitypress.co.uk/uploads/docs/400285.pdf

http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-ROORKEE/BASIC-ELECTRONICS/lecturers/lecture_33/lecture33_page1.htm

http://en.wikipedia.org/wiki/Wilson_current_mirror

http://bwrc.eecs.berkeley.edu/classes/ee140/Lectures/3_current_src.pdf

http://www.odyseus.nildram.co.uk/RFIC_Subcircuits_Files/CMOS_Cascode_Current_Mirror.pdf

http://en.wikipedia.org/wiki/Cascode

http://en.wikipedia.org/wiki/Active_load

http://kaflatooni.yasna.com/current_mirror_ref.pdf