Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
toc sach » hoc sach, doc sach, thuoc sach
thuc van » thuc vat, thuc dan, thuc va
van hanh » van thanh, ban hanh, van anh
hieu ve » hieu va, hieu van
ve tham » va tham, ve cham, vi tham
cua tre » cuu tre, cua triet, dua tren
y lang » _ lang, tay lang, yen lang
o lang » hoa lang, hoi 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: toc sach ((y lang) or (o lang)) van hoa. hieu ve tham thuc van hanh vi ((cua tre) OR (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((y lang) OR (o lang)) van hoa. hieu ve tham thuc van hanh vi ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((y lang) or (o lang)) van hoa. hieu ve tham thuc van hanh vi ((cua tre) OR (cua te))".
• Adding a wildcard symbol may retrieve word variants: toc sach ((y lang) or (o lang)) van hoa. hieu ve tham thuc van hanh vi ((cua tre) OR (cua te))*.