They should be numbered according to their sequence in the text. References should be made in the text to each figure. Each illustration should be accompanied by a caption. Explanations should be given in the typewritten legend. No letter, number or symbol should be less than 5 mm high.
Photographs are only acceptable if they have good contrast and intensity.
Color illustrations cannot be included. Subscripts and superscripts should be set off clearly. The numbers identifying mathematical expressions should be placed on the right-hand side and in parentheses.