a few of the journal articles, though many of the reports from human rights groups, and the sheer volume of independent reports from different new outlets (big and small) is also rather compelling (as well as bellingcat's reporting):

• https://www.tandfonline.com/doi/full/10.1080/14623528.2020.1848109
• https://www.jpolrisk.com/break-their-roots-evidence-for-chinas-parent-child-separation-campaign-in-xinjiang/
• https://link.springer.com/article/10.1007/s12140-015-9224-8