These are general and more specialised resources.
Note that sometimes books and scores may have an accompanying CD.
The Garland Encyclopedia of World Music is an authoritative source. A direct link to the relevant chapter is given below.
The Grove Encyclopedia in Oxford Music Online is another good source. Click on the link, log in with your student ID and StudentWeb password, then search. The subject entry for Cuba covers Son. There are other useful subject entries on Clave and Salsa.
You can stream music from Music Online.
Click on the link below. You'll need to log in with your student ID and StudentWeb password. Then do an Advanced Search, searching by Afro-Cuban in the Genre box.