Abbreviations should be avoided in the running text. Common abbreviations (see Duden) such as etc., cf., e.g. ... can be used without problems. Specially introduced abbreviations should be used very rarely (put yourself in the reader's position).

The paper should use standardised symbols. If symbols from other sources are used, they should be adapted to the symbols used in the paper, while maintaining consistency of content (e.g. units of measurement, statistical symbols). This does not apply to direct quotations.