Wu jing, or Five Classics.

Confucius systematically organized his teaching material into six parts, which later became the fouding scripture, Six Classics. Among the Six Classics, the legendary Classic of Music was lost under the reign of First Qin Emperor. Thus we have only Five Classics, that is Classic of Poetry (Shi Jing), the Book of Documents (Shu Jing), the Book of Rites (Li Ji), the Book of Changes (Yi Jing), and the Spring and Autumn Annals (Chun Qiu).

For the Book of Change, I would recommend the website Yellowbridge which presents Chinese and English side by side, it's very useful if you're confused by various translation/interpretations and try to make your own judgement from the original Chinese text. And I also recommend this website by James DeKorne, which collects more than 8 different versions of translations and paraphrases for purpose of scholarly comparison.