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