Book-for is a website created for the purpose of collecting documents related to technical and scientific subjects to provide convenience to students and current engineers who wish to study, research, and supplement their knowledge and skills. It is better to develop oneself to become a real technical expert. For collected documents, such as : (Electrical Guide : control system, installation and calculation, power system, relay protection, solar energy,...), (Electronic Guide : analog and digital, arduino, circuit design components, electronic control system, micro electronic,...), (Civil Construction Guide : concrete construction, foundation design, mechanics, reinforced concrete, strength design, structural design,...), (Mechanisms Guide : air conditioning, bearing, compressor, gears, mechanical, pump,...), (IT Guide : database systems, game programming, network, program language,...)