Demography: Measuring and Modelling Population Processes.
—Samuel H. Preston (2001)
This book presents and develops the basic methods and models that are used by demographers to study the behavior of human populations. The procedures are clearly and concisely developed from first principles, and extensive applications are presented.
The authors focus on quantitative procedures for studying the growth and structure of populations, including measurement of fertility and mortality, population projection, and equilibrium models.
The book also covers procedures for evaluating data quality and estimating demographic parameters when conventional data are deficient. It will provide a comprehensive introduction to demographic methods for all students and researchers in this subject.

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Page 115 (section 5.5) is a good place for understanding Total Fertility Rate (TFR) and Replacement Fertility Rate (RFR).
However the entire book is of tremendous value for White nationalists.