Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
thuc day » thuc dan
hang tai » dung tai
han tai » nhan tai, van tai, toan tai
cuu tre » cua tre, cau tren, cau treo
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
ky hang » ky nang, ly hang, ky dang
va nam » van nam, ha nam, va nay
va hoe » van hoe, va hoc, va hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ky hang va hoe. hieu va nam ((thuc vat) or (thuc day)) ((han tai) OR (hang tai)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky hang va hoe. hieu va nam ((thuc vat) OR (thuc day)) ((han tai) OR (hang tai)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ky hang va hoe. hieu va nam ((thuc vat) or (thuc day)) ((han tai) OR (hang tai)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: doc sach ky hang va hoe. hieu va nam ((thuc vat) or (thuc day)) ((han tai) OR (hang tai)) cuu tre*.