The h-index has received wide attention in recent years. The area under the citation function is divided by the h-index into three parts, representing h-squared, excess and h-tail citations. The h-index by itself does not carry information for excess and h-tail citations, which can play an even more dominant role than h-index in determining the citation curve, and therefore it is necessary to examine the relations among them. A triangle mapping technique is proposed here to map the three percentages of these citations onto a point within a regular triangle. By viewing the distribution of mapping points, shapes of the citation functions can be studied in a perceivable form. As an example, the distribution of the mapping points for 100 most prolific economists is studied by this technique.