Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
tu sach » thu sach, su sach, te sach
xanh di » danh di, vanh dai, xanh tai
va xanh » va danh, va hanh, va anh
cac dac » cac dan, cac dai, cac bac
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac nuoc
cuu tre » cua tre, cau tren, cau treo
nang o » nang co, nang ho, nang ro
di cuu » di cau, di cua, dinh cuu
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (thuat sach)) ky nang o hoi. hieu va ((cac duc) OR (cac dac)) va xanh di cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thuat sach)) ky nang o hoi. hieu va ((cac duc) OR (cac dac)) va xanh di cuu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thuat sach)) ky nang o hoi. hieu va ((cac duc) OR (cac dac)) va xanh di cuu tre*".