Text
In the text - a number is allocated to each reference and this is inserted in the text as a superscript number or in parentheses. For example:
"Double flowers are being sought by one breeder (10), but others consider the single flower more beautiful. The hybrid clone 'Annie J. Hemming' (11) frequently produces six or seven petals rather than the five typical of the genus Hibiscus."
If a reference is cited more than once, the same number is used.