Pungello, E. P., Iruka, I. U., Dotterer, A. M., Mills-Koonce, R., & Reznick, J. S. (2009). The effects of socioeconomic status, race, and parenting on language development in early childhood. Developmental psychology, 45(2), 544.
Vernon-Feagans, L., Pancsofar, N., Willoughby, M., Odom, E., Quade, A., Cox, M., & Family Life Key Investigators. (2008). Predictors of maternal language to infants during a picture book task in the home: Family SES, child characteristics and the parenting environment. Journal of applied developmental psychology, 29(3), 213.
Hoff, E. (2003). The Specificity of Environmental Influence: Socioeconomic Status Affects Early Vocabulary Development Via Maternal Speech. Child Development, 74(5), 1368-1378.
If you are unable to access the full text of these papers, I can send it to you for your attention only:
Raviv, T., Kessenich, M., & Morrison, F. J. (2004). A mediational model of the association between socioeconomic status and three-year-old language abilities: The role of parenting factors. Early Childhood Research Quarterly, 19(4), 528-547.
Hoff, E., & Tian, C. (2005). Socioeconomic status and cultural influences on language. Journal of communication Disorders, 38(4), 271-278. Journal of communication Disorders, 38(4), 271-278.
First, look at : https://www.ncbi.nlm.nih.gov/books/NBK402020/. I think that we in the sociology of education tend to see a major difference in attitudes about schooling that really do tend to track with SES. In the U.s., low-income parents were often poorly educated themselves, and this has generally produced two related attitudes: 1) that they are not capable of helping their children learn because 'they don't know what they don't know'; and, 2) because the teacher is 'educated', it is the teachers job (exclusively, not just primarily) to teach the child.
Included in this are cultural connect/disconnect tones, such as the statement that I once heard from a former vet and dad of Appalachian heritage: "The state tells me I have to send my kids to school, so I do..."