The APA Style (.pdf) was developed by the American Psychological Association and is a system widely used in the social sciences.
The Chicago Style (.pdf) was developed by the Chicago Press and is a system used across the humanities.
The IEEE system (.pdf) is used in papers published by the institute of Electrical and Electronic Engineers and is widely used in the fields of computer science, software development and information technology.
The MLA system (.pdf) was developed by the Modern Language Association and is used mostly in the humanities.
OSCOLA (.pdf) is short for 'Oxford University standard for the Citation of Legal Authorities' and is used by Law schools across the UK.
The Vancouver style (.pdf) was established in Canada by the International Committee of Medical Journal Editions (CMJE).It is commonly used in medicine and science research.