In fact that scientific article about comparison is quite a nonsense, it is hard to compare yuzu, Ilya correctly used word "average", yuzu do not grow true from seed and there are loads of cultivars, with great variation of size. Yuzu Kito is considered the biggest one, but there are cultivars with half of his size. The diameter of yuzu varies from 4 to 10 cm, depending from cultivar.
Here is yuzu which came from former USSR to former Czechoslovakia selection under name yuzu no. 1 -754.
It has very small fruits and lot of seeds, but juice has great taste, sweet/sour mix of lemon and mandarin.
In picture from net you can see comparsion of Hana yuzu 花ユズ, Hong yuzu aka yuzu kitó 本柚子 and Shishi yuzu 獅子柚子 (citrus pseudogulgul).