Here is a link through Bee Culture Magazine about Using Oxalic Acid for fall Varroa mite treatment.
https://www.beeculture.com/using-oxalic-acid/
The link below is to the EPA Label about Oxalic Acid.
The EPA Label states how to properly use Oxalic Acid for the treatment of Varroa mites on Honey Bees. The label lists all the hazards in using the product and the use of the proper PPE. The one thing that is murkey is the dosage. Being it is scientific and not used for baking a cake, all of the mixtures are by weight or by metric volumes.