1.   One cannot therefore measure their use or their citation frequency, and the work is not normally published in any form.

2.   Non-controversial works produce lower citation frequencies than disputed or erroneous papers.

3.   He derives a family of surge-wave-shaped curves, according to the different types of citation frequency found in the literature, from a mathematical equation.

4.   Conversely, supervisors may feel that their contributions to published papers are undervalued if their citation frequencies do not reflect their influence on research programmes.