Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
tham luc » than luc, tham nuoc, nhan luc
hanh tai » thanh tai, hang tai, han tai
lang van » dang van, tang van, hoang van
cuu tre » cua tre, cau tren, cau treo
tai cuu » tai cuc, tai buu, tai cua
va hanh » van hanh, va thanh, va danh
hieu va » lieu va, hieu qua
lang xa » lang ha, dang xay
sac ky » cac ky, sai ky
te sac » te sach, te cac, te san

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sac ky ((lang xa) or (lang van)) hoi. hieu va ((tham luc) OR (tham thuc)) va hanh tai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky ((lang xa) OR (lang van)) hoi. hieu va ((tham luc) OR (tham thuc)) va hanh tai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sac ky ((lang xa) or (lang van)) hoi. hieu va ((tham luc) OR (tham thuc)) va hanh tai cuu tre".
• Adding a wildcard symbol may retrieve word variants: te sac ky ((lang xa) or (lang van)) hoi. hieu va ((tham luc) OR (tham thuc)) va hanh tai cuu tre*.