Look for ethnobotany textbooks. Titles like:
These are legal, available as PDFs for purchase, and academically rigorous. Buka Ya Dingaka Pdf Download
The traditional way to learn bongaka (healing arts) is through apprenticeship. Find a reputable healer in your area. Offer to assist with chores and show humility. You will learn far more in one month of practical training than from any PDF. Look for ethnobotany textbooks
Many so-called PDFs circulating on Telegram, WhatsApp, or shady websites are fabricated. They mix real herbs with dangerous substances, or give incorrect divination instructions, misleading readers. These are legal, available as PDFs for purchase,