books.google.com - Despite the increasing use of computers, the basic need for mathematical tables continues. Tables serve a vital role in preliminary surveys of problems before programming for machine operation, and they are indispensable to thousands of engineers and scientists without access to machines. Because of...https://books.google.com/books/about/Handbook_of_Mathematical_Functions.html?id=MtU8uP7XMvoC&q=EXPONENTIAL+INTEGRALS&utm_source=gb-gplus-shareHandbook of Mathematical Functions