Perhaps you should try some spelling variations:
cau thuc » cau truc, cuu thuc, can thuc
thai cua » than cua, tai cuc, tri cua
van hanh » van thanh, ban hanh, van anh
tay thai » lay thai, toc thai, y thai
thuc van » thuc vat, thuc dan, thuc va
so sach » so sanh, bo sach, co sach
tai cua » tai cuc, tri cua, dai cua
hieu ve » hieu va, hieu van
sach ly » sach y, sach lo, sach ty
tao hoi » tao khoi, tao boi, tay hoi
ly hang » ly quang
ve cau » ke cau, va cau, ve cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ly hang ((tao hoi) or (tay thai)). hieu ve cau thuc van hanh ((tai cua) OR (thai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ly hang ((tao hoi) OR (tay thai)). hieu ve cau thuc van hanh ((tai cua) OR (thai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ly hang ((tao hoi) or (tay thai)). hieu ve cau thuc van hanh ((tai cua) OR (thai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: so sach ly hang ((tao hoi) or (tay thai)). hieu ve cau thuc van hanh ((tai cua) OR (thai cua)) tre*.