Charadrius is a genus of plovers, a group of wading birds in the family Charadriidae, in the order Charadriiformes. 
The genus name Charadrius is a Late Latin word for a yellowish bird mentioned in the fourth-century Vulgate. 

1/ Long-billed plover (Choi choi lớn, Charadrius placidus)

2/ Little ringed plover (Choi choi nhỏ, Charadrius dubius) 
The specific dubius is Latin for doubtful, since Sonnerat, writing in 1776, thought this bird might be just a variant of common ringed plover.