The term “reference service” is defined simply as personal assistance provided to library users seeking information. Individuals who hold a master’s degree in the field of library and information sciences or information studies typically provide the service.

Use reference books (also called reference or background sources, or resources) to get quick specific facts or information or an overview of a subject. Some examples of reference sources are: dictionaries, encyclopedias, bibliographies, almanacs, directories, atlases, and handbooks. These can be online or in print.

Reference sources such as dictionaries, encyclopedias, almanacs, atlases, etc. are research tools that can help you with your paper or project. Reference sources are designed to be consulted rather than read through. Reference materials can be arranged alphabetically, topically, or chronologically.

Characteristics of Reference Books:

• They are intended primarily for occasional consultation.
• They are consulted for definite items of information.
• The information included in them is collected from a vast number of sources.
• It is a miscellany of information and facts.

Reference materials are of critical importance in establishing comparability and accuracy of analytical results between different locations and over time.

A reference group is a group to which an individual or another group is compared, used by sociologists in reference to any group that is used by an individual as a standard for evaluating themselves and their own behavior.

An example of a reference group is a group of people who have a certain level of affluence. For example, an individual in the U.S. with an annual income of $80,000, may consider himself affluent if he compares himself to those in the middle of the income strata, who earn roughly $32,000 a year.

There are three basic types of reference groups: informational, utilitarian, and value- expressive.

A reference group that an individual admires or aspires to and uses as a standard representing opinions, attitudes, or behaviour patterns to emulate.

Herbert Hyman

The following characteristics of Reference Group Behaviour may be pointed out: (i) The individual or group considers the behaviour of the other individual or group as ideal behaviour and imitates it. (ii) The individual or group compares himself or itself with the other individual or group.

We call such groups in-groups. Fraternities, sororities, sports teams, and juvenile gangs are examples of in-groups. Members of an in-group often end up competing with members of another group for various kinds of rewards. This other group is called an out-group.

In the relationship among the members of in group they display co-operation, good will, mutual help and respect for each other. Members of in group possess a sense of solidarity a feeling of brotherhood. In group members are always ready to sacrifice themselves for the group.

1 : a subordinate group whose members usually share some common differential quality. 2 : a subset of a mathematical group that is itself a group.

Subcultures are values and norms distinct from those of the majority and are held by a group within a wider society. In the United States, subcultures might include hippies, Goths, fans of hip hop or heavy metal and even bikers – the examples are endless. A biker gang is an example of a subculture.

Normal subgroups are important because they (and only they) can be used to construct quotient groups of the given group. Furthermore, the normal subgroups of G are precisely the kernels of group homomorphisms with domain G, which means that they can be used to internally classify those homomorphisms.