If you're looking for a verified PDF copy of the ISO 18593 standard, I recommend:
ISO 18593 is an international standard that provides guidelines for the microbiological analysis of food and animal feeding stuffs. The standard outlines the requirements for the preparation of samples, the selection of test methods, and the interpretation of results. It covers a wide range of microorganisms, including bacteria, viruses, and parasites, that can contaminate food and animal feeding stuffs. If you're looking for a verified PDF copy