The citations retrieved will contain all of your concepts. OR broadens your search by connecting synonyms. The records retrieved will contain at least one of your synonyms. Normally, proximity operators cannot be used with nested expressions. The symbols used will vary from one system to another.
Perspective refers to the angle or approach from which authors engage their subjects.
Bias refers to a special interest or personal angle. Attitude refers to the author's position on the subject. A wide range of material useful in Web searching, including recommended sites, tutorials, search engine links and information, and criteria for evaluating information found on the Web.