Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
va trien » va truyen, va thiet, va tuyen
tay lang » tai lang, tay tang, tay quang
hanh sai » hanh san, hanh tai, danh sai
hieu van » hieu va, thien van, lieu va
te sach » toc sach
va hanh » van hanh, va thanh, va danh
van cam » van nam, van lam, van cau
thuc va » thuc vat, thuc dan, thuc day
y lang » o lang, _ lang, yen lang
cua te » cua tu

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 ((y lang) OR (tay lang)) xa hoi. hieu van cam thuc va hanh sai ((va trien) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((y lang) OR (tay lang)) xa hoi. hieu van cam thuc va hanh sai ((va trien) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((y lang) OR (tay lang)) xa hoi. hieu van cam thuc va hanh sai ((va trien) or (cua te))".
• Adding a wildcard symbol may retrieve word variants: te sach ((y lang) OR (tay lang)) xa hoi. hieu van cam thuc va hanh sai ((va trien) or (cua te))*.