Age Group is a very important set of limits because very few subject headings have an age group implied in the heading. Use this limit to restrict a search to a particular age group, such as geriatric populations. Limiting by age group automatically limits by human. Animal is used to restrict the search to studies done on a specific animal. Publication Type limits to documents of a specific type.
Language limits to documents in that particular language.
Human , Animal , Male , Female , Review Article , and Abstract limits are self-explanatory. This is NOT a good choice for most searches. The only people who should use this limit are those who run the same search every month. Year of Publication is also self-explanatory. For this example, limit the asthma search to records on human studies that are in French.