Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
thuc cay » thuc day, thuc can, thuc cao
cay vanh » cay lanh, cay xanh, cac van
vanh dai » van dai, vanh tai, lanh dao
sach va » sach xa, sach ha, sach dao
cao hoi » cau hoi, co hoi, cao hoc
va tham » van tham, va cham, va thanh
sach v » sach y, sach 2, sach vay
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: su ((sach v) OR (sach va)) nang cao hoi. lieu va tham thuc cay vanh dai cua su~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach v) OR (sach va)) nang cao hoi. lieu va tham thuc cay vanh dai cua su".
• Adding a wildcard symbol may retrieve word variants: su ((sach v) OR (sach va)) nang cao hoi. lieu va tham thuc cay vanh dai cua su*.