Starman Jones

The stars were closed to Max Jones. To get into space you either needed connections, a membership in the Guild, or a whole lot more money than Max, the son of a widowed, poor mother, was every going to have. What Max does have going for him are his uncle’s prized astrogation manuals—book on star navigation that Max literally commits to memory word for word, equation for equation.
From the First Golden Age of Heinlein, this is the so-called juvenile (written, Heinlein always claims, just as much for adults) that started them all and made Heinlein a legend for multiple generations of readers.