Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, han tai
lam duoc » nam duoc, luat duoc, lam thuoc
lang xa » lang ha, dang xay, lang van
sach ky » sac ky, sach y, sach ty
van lam » van nam
duoc va » nuoc va, duc va, duoc ma
va hanh » van hanh, va thanh, va danh
nang ma » tang ma, sang ma, nang cao
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: doc sach ky ((((nang ma) or (lang xa))) or (nang x)) hoi. hieu van lam duoc va hanh tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky ((((nang ma) OR (lang xa))) OR (nang x)) hoi. hieu van lam duoc va hanh tai cua te.
• Adding a wildcard symbol may retrieve word variants: doc sach ky ((((nang ma) or (lang xa))) or (nang x)) hoi. hieu van lam duoc va hanh tai cua te*.