http://www4.ncsu.edu/~mtchu/Teaching/Lectures/MA530/chapter8.pdf

http://www.mathcs.emory.edu/~haber/math315/chap5.pdf

http://www.physics.ohio-state.edu/~ntg/780/readings/hjorth-jensen_notes2009_07.pdf

http://www2.math.umd.edu/~dlevy/classes/amsc466/lecture-notes/integration-chap.pdf

http://www.cs.ntou.edu.tw/indexs/files/fslin/SC/SctcCh4st.pdf

http://physics.clarku.edu/courses/125/gtcdraft/chap11.pdf

http://www.sml.ee.upatras.gr/UploadedFiles/BOOK-CK/02-BasicPrinciples.pdf

http://www.physics.ohio-state.edu/~ntg/780/readings/hjorth-jensen_notes2011_05.pdf