Factors and determinants of primary care to tertiary care referrals in Singapore: A multi-centre analysis using artificial intelligence-powered large language models - Sky Wei Chee Koh; Jasper Yi Xuan Huang; Joelle Lam; Si Hui Low; Jun Cong Goh; Ge Ji; Xin Jin; Howard Bauchner; Yii Jen Lew (PLoS ONE, 2026)