Here are entered works on technological, economic, or legal conditions of a market which raise the costs of firms wanting to enter the market above those of firms already in the market, or which otherwise make new entry difficult.
--subdivision Registers under names of countries, cities, etc., individual corporate bodies and families, and under classes of persons, ethnic groups, individual wars, and topical headings
Here are entered works on the interrelationships of organisms and their environment, including other organisms. Works on the composite of physical, biological, and social sciences concerned with the conditions of the environment and their effects are entered under Environmental sciences. Works on the relationship of humans to the natural environment are entered under Human ecology. Works on the relationship of humans to their sociocultural environment are entered under Social ecology. --subdivision Environmental aspects under subjects, e.g. Agricultural chemicals--Environmental aspects; Nuclear power plants--Environmental aspects; and headings beginning with the word Ecological
