Singh, Virendra. “Influence of Indole Acetic Acid and Indole Butyric Acid on Seed Germination of Spruce”. Indian Forester 116, no. 6 (June 1, 1990): 450–454. Accessed July 10, 2025. https://indianforester.co.in/index.php/indianforester/article/view/8851.