I want to study chi square test of homogeneity from any authentic source- book / website especially problems where samples are compared for more than one attribute. What are some relevant sources? Relevant background: I was studying examples from random online sources before I saw this book in which a second X2 has been calculated and has been substracted from the principle X 2 (the one we usually find). This is inconsistent to the examples I saw online. Infact we are being taught the latter process.