Hi, I'm a History student from Argentina and I always had the doubt about the accuracy of Robert Graves in his Greek Myths. I wanted to know if he quotes his sources somewhere since my edition of the myths doesn't have any mention to Historic or Anthropologic works, neither of primary sources such as Theogony, Odyssey, etc. Thanks and sorry for the bad English
If you get a full edition of his book, there are notes, in which he cites primary sources, including big names such as Hesiod, Homer, etc. but also scholia and later sources. But he cites by section, rather than individual sentence, so it's not always clear what source he is using for what particular detail.
But as I'm sure the links someone provided will show, no one should use Graves as a source for Greek mythology. If you're looking for good sources, try Grimal's book (which has been translated into Spanish: https://www.amazon.com/Mitologia-Mythology-Studios-Studies-Spanish/dp/8475095305/ref=sr_1_2?keywords=grimal+greek+mythology&qid=1582153777&sr=8-2) or Gantz's much more detailed work (https://www.amazon.com/s?k=early+greek+myth+gantz&crid=3CUHEWGP2HLLU&sprefix=gantz+earl%2Caps%2C179&ref=nb_sb_ss_i_1_10).
Not to discourage any further discussion, but some previous answers have thoughts on Robert Graves:
How reliable is Robert Graves' commentary in 'The Greek Myths'? by u/XenophonTheAthenian
Pre-Bronze age Greek religion; why did Robert Graves speak of Pelasgians? by u/Alkibiades415