Perhaps you should try some spelling variations:
thien hach » thien thanh
hien hanh » dieu hanh
cau tren » cu tren, dau tren, ca tren
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
va dan » ca dan, va dao, va dau
dan du » dan dau, danh du, dan su
du cau » cu cau, da cau, di cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky nang ma hoi. hieu ((hien hanh) or (thien hach)) nuoc va dan du cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang ma hoi. hieu ((hien hanh) OR (thien hach)) nuoc va dan du cau tren.
• Adding a wildcard symbol may retrieve word variants: vu sach ky nang ma hoi. hieu ((hien hanh) or (thien hach)) nuoc va dan du cau tren*.