Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, hieu ve
hanh tai » thanh tai, hang tai, han tai
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
truc va » thuc vat, trung va
thuc va » thuc vat, thuc dan, thuc day
tai cua » thai cua, tai cuc, tri cua
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 ky nang ma hoa. ((hieu van) or (lieu va)) cau ((truc va) OR (thuc va)) hanh tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang ma hoa. ((hieu van) OR (lieu va)) cau ((truc va) OR (thuc va)) hanh tai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang ma hoa. ((hieu van) or (lieu va)) cau ((truc va) OR (thuc va)) hanh tai cua te".
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang ma hoa. ((hieu van) or (lieu va)) cau ((truc va) OR (thuc va)) hanh tai cua te*.