Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
ban thanh » ban hanh, ban hang
tham thuc » nham thuc, pham thuc, tam thuc
nang mai » nang ma, nang tai, nang cai
thanh di » thanh doi, thanh de, thanh do
lang mai » lang dai, lang hai, lang man
thuc ban » thuoc ban, thuc dan, thu ban
hieu va » lieu va, hieu qua
va tham » van tham, va cham, va thanh
di cua » dai cua, doi cua, de cua
cua su » qua su

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cac) or (thuat sach)) ky ((nang mai) OR (lang mai)) hoi. hieu va tham thuc ban thanh di cua su~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cac) OR (thuat sach)) ky ((nang mai) OR (lang mai)) hoi. hieu va tham thuc ban thanh di cua su.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cac) or (thuat sach)) ky ((nang mai) OR (lang mai)) hoi. hieu va tham thuc ban thanh di cua su".
• Adding a wildcard symbol may retrieve word variants: ((tu cac) or (thuat sach)) ky ((nang mai) OR (lang mai)) hoi. hieu va tham thuc ban thanh di cua su*.