For this type of task, I find it best to go to Google Scholar. If you put in the title of the paper behind the first link you'll find the 1991 paper available from
https://www.researchgate.net/profile/Nazli_Baydar/publicatio... .
You'll also see that it's been cited by 611 papers. It's usually a bit odd to reference a 27 year old paper as a source because additional research since then has likely given more insight into the problem.
Pulling one out at semi-random, http://onlinelibrary.wiley.com/doi/10.1111/cch.12238/full argues "more hours in non-parental child care were associated with better language abilities. However, more hours in care in the first year of life were associated with less language proficiency at ages 1 to 1.5. At later ages, this effect disappeared and language proficiency increased. Furthermore, children who spent more hours in centre-based care had better language scores than children in home-based care."
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.704... summarizes a number of related reports:
> O’Brien Caughy et al. (1994) report that entrance into daycare before the first birthday was associated with higher test scores (Peabody Individual Achievement Tests) for lower income children and lower test scores for higher income children. For the U.K. Gregg et al. (2005) find that children who receive informal care from friends and relatives in the first 18 months of life combined with full time maternal employment have lower cognitive outcomes. ... Finally, Loeb et al. (2007) find that entry into non-parental center based care before the age of one can lead to problem behavior. Magnuson et al. (2007), Baker et al. (2008), Datta Gupta and Simonsen (2010), and the research summarized in Belsky (2006) provide further evidence that non-parental care can have negative behavioral effects in some contexts.
Or there's https://www.ncbi.nlm.nih.gov/pubmed/11016559 which says:
> After adjusting for child care quality, cumulative experience in center-based care was associated with better outcomes than was participation in other types of care. The amount of time children spent in care was not related to outcomes. Children in exclusive maternal care did not differ systematically from children in child care. Tests for lagged relations of earlier child care experiences to later performance (adjusting for current child care) showed that language stimulation predicted subsequent cognitive and language performance 9 to 12 months later. Although children in center care at age 3 performed better than children in other types of care, earlier experience in child care homes was associated with better performance at age 3 than was experience in other types of care.
These would appear to be counter to your statement that "Sending children to day care for large amounts of their youth has been shown to be highly detrimental to their development." More specifically, once the child is about 18 months old, there appears to be positive effects of daycare and non-parental care.
That "Family Facts" link is from The Heritage Foundation, which has a mission to "formulate and promote conservative public policies based on the principles of free enterprise, limited government, individual freedom, traditional American values, and a strong national defense."
I can't help but think there is a bias in which topics to report and which evidence to present.
One way to assuage my doubts would be if the reports had a link to the primary research literature. However, the only citation is to "a FamilyFacts.org Report by Jenet Jacob Erickson, researcher specializing in maternal and child wellbeing and former assistant professor in the School of Family Life at Brigham Young University. Her report reviewed key findings from 30 years of research on child care and children’s social– emotional development."
This does not appear to be a peer-reviewed report. While peer-review has its problems, I again can't help but wonder about any possible cherry picking.
Given the editorials by the author, at https://www.deseretnews.com/author/23012/Jenet-Jacob-Erickso... , I know that we have very different biases.
The last link is to Stefan Molyneux, who is often characterized as "alt-right" or "far-right". As an anti-feminist, I suspect he is biased towards research which keeps middle-class women at home to raise children.
In any case, unlike Erickson, he is (like both you and me) also not an expert on this subject.