Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
cau tren » cu tren, dau tren, ca tren
toc sach » hoc sach, doc sach, thuoc sach
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
cac toc » cac toi, cac nuoc, cac thoi
va danh » va dinh, va dan, va hanh
danh di » danh du, xanh di, danh dien
ma hoi » mai hoi, xa hoi, ma hoa
ve cac » va cac, vien cac
toc va » hoc va, toc ta, tuc va
di cau » da cau, diem cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((((te sach) OR (toc sach))) or (thuat sach)) ky nang ma hoi. hieu ve cac toc va danh di cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((((te sach) OR (toc sach))) OR (thuat sach)) ky nang ma hoi. hieu ve cac toc va danh di cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((te sach) OR (toc sach))) or (thuat sach)) ky nang ma hoi. hieu ve cac toc va danh di cau tren".
• Adding a wildcard symbol may retrieve word variants: ((((te sach) OR (toc sach))) or (thuat sach)) ky nang ma hoi. hieu ve cac toc va danh di cau tren*.