Perhaps you should try some spelling variations:
thanh vai » thanh hai, thanh van, thanh tai
hoc sach » hoc sinh, hoc cac, hoc anh
va thanh » gia thanh, ban thanh, va tinh
tang mai » tang ma, tang tai, lang mai
vai cua » dai cua, hai cua, lai cua
cham lo » cham o, cam lo, cham soc
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
tu sach » thu sach, su sach, te sach
cua tre » cua te, cuu tre, cua triet
cam ly » tam ly, cam ky, cam lo
y tang » ky tang, 6 tang, 7 tang

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) or (tu sach)) y tang mai hoi. hieu ve ((cham lo) or (cam ly)) va thanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (tu sach)) y tang mai hoi. hieu ve ((cham lo) OR (cam ly)) va thanh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((hoc sach) or (tu sach)) y tang mai hoi. hieu ve ((cham lo) or (cam ly)) va thanh vai cua tre*.