The Mythical Man-month

The Mythical Man-Month: Essays on Software Engineering is a book on software engineering and project management by Fred Brooks
first published in 1975, with subsequent editions in 1982 and 1995. Its
central theme is that "adding manpower to a late software project makes
it later." This idea is known as Brooks's law, and is presented along with the second-system effect and advocacy of prototyping.

Brooks's observations are based on his experiences at IBM while managing the development of OS/360. He had added more programmers
to a project falling behind schedule, a decision that he would later
conclude had, counter-intuitively, delayed the project even further. He
also made the mistake of asserting that one project—involved in writing
an ALGOL compiler—would
require six months, regardless of the number of workers involved (it
required longer). The tendency for managers to repeat such errors in
project development led Brooks to quip that his book is called "The
Bible of Software Engineering", because "everybody quotes it, some
people read it, and a few people go by it".[1]