Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
ly quang » le quang
cac thuc » cach thuc, cac thu, can thuc
vat hanh » vat thanh, van hanh, va hanh
hanh tai » thanh tai, hang tai, han tai
hieu va » lieu va, hieu qua
tai duc » tai cuc, mai duc, tai du
duc tre » duoc tren, duc tien

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ((ly hang) or (((ly quang) OR (vu quang)))) xa hoi. hieu va cac thuc vat hanh tai duc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ((ly hang) OR (((ly quang) OR (vu quang)))) xa hoi. hieu va cac thuc vat hanh tai duc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ((ly hang) or (((ly quang) OR (vu quang)))) xa hoi. hieu va cac thuc vat hanh tai duc tre".
• Adding a wildcard symbol may retrieve word variants: hoc sach ((ly hang) or (((ly quang) OR (vu quang)))) xa hoi. hieu va cac thuc vat hanh tai duc tre*.