| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Ruta graveolens | Plant | -- | -- | * | |
| Ferula alliacea | Plant | -- | -- | * | |
| Citrus limon | Fruit Essent. Oil | -- | -- | Jim Duke's personal files. | |
| Citrus spp | Plant | -- | -- | Jeffery B. Harborne and H. Baxter, eds. 1983. Phytochemical Dictionary. A Handbook of Bioactive Compounds from Plants. Taylor & Frost, London. 791 pp. | |
| Citrus limon | Essential Oil | -- | 29.0 | * | |
| Angelica archangelica | Root | -- | 13.0 | * | |
| Angelica dahurica | Root | -- | -- | * |