Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
danh ve » dinh ve, hanh ve, anh ve
ve cam » ve cham, ve cac, va cam
xuc va » tuc va, luc va, xac va
ve cau » ke cau, va cau, ve cac

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang x) OR (nang ma)) hoi. hieu ve cam ((xuc va) OR (duc va)) danh ve cau tren~.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang x) or (nang ma)) hoi. hieu ve cam ((xuc va) or (duc va)) danh ve cau tren*.