P. N. Ravindran

• Ginger
• Black pepper
• Cardamom
• Black Pepper, Piper Nigram (Medicinal & Aromatic Plants--Industrial Profiles)
• Cinnamon and cassia
• Ginger
• Nominal composition in Malayalam
• Turmeric
• Encyclopedia of Herbs and Spices
• Handbook of Spices in India
• Nominal composition in Malayalam
• Turmeric