Books focusing on the topic of Mother/Son incest.

There are many, many books covering different taboo sexual relationships, but almost none on incestuous relationships between mothers & sons.

Here is probably not the best place to discuss why, but I will point out there are plenty of women writing romance fiction about father/daughter interactions, and almost none write about mother/son, which I find interesting.

Guidelines for this list:
- Explicit depictions/descriptions of sex and/or romance between mothers and sons. Not alluded to, but explored and depicted.
- Literary books only. Highbrow or lowbrow is fine. Erotica is acceptable, but no straight pornography.
- Fiction only.
- Legal content only, nothing illegal.