1. W. BROWN, 1964 . Process for separating tocopherols and sterols from deodorizer sludge and the like. U.S. Patent 3,153,054.
2. W. BROWN, and K. H. MEAG, 1963 . Process for recovery of tocopherols and sterols. U.S. Patent 3,108,120.
3. W. BROWN, and F. E. SMITH, 1964 . Process for separating tocopherols and sterols from deodorizer sludge and the like. U.S. Patent 3,153,055.
4. A. GAPOR, L. W. LEONG, and A. ONG, 1989 . Production of high concentration tocopherols and tocotrienols from palm oil by-products. European Patent Application 0,333,472A2.