Perhaps you should try some spelling variations:
nham thuc » nhan thuc, nam thuc, nham thu
thu sach » tu sach, thuat sach, thuoc sach
thuc van » thuc vat, thuc dan, thuc va
tang mai » tang ma, tang tai, sang mai
dinh vai » dinh van, dinh vi, dinh va
lang mai » lang dai, lang hai, lang man
van dinh » van minh, van dich, va dinh
hieu van » hieu va, thien van, lieu va
vai cua » dai cua, hai cua, lai cua
hieu ve » hieu va
sach ky » sac ky, sach y, sach ty
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: thu sach ky ((tang mai) or (lang mai)) hoi. ((hieu ve) OR (hieu van)) nham thuc van dinh vai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((tang mai) OR (lang mai)) hoi. ((hieu ve) OR (hieu van)) nham thuc van dinh vai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky ((tang mai) or (lang mai)) hoi. ((hieu ve) OR (hieu van)) nham thuc van dinh vai cua te".
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((tang mai) or (lang mai)) hoi. ((hieu ve) OR (hieu van)) nham thuc van dinh vai cua te*.