Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
dang xay » dang van, van xay
lam duoc » nam duoc, luat duoc, lam thuoc
hieu van » hieu va, thien van, lieu va
van lam » van nam
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
duoc va » nuoc va, duc va, duoc ma
han tai » hang tai, nhan tai, van tai
tai cua » thai cua, tai cuc, tri cua
va han » va phan, van han, va hanh
cua tu » cua tuc, cua su, cua cu

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 (dang xay))) or (nang x)) hoi. hieu van lam duoc va han tai cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky ((((nang ma) OR (dang xay))) OR (nang x)) hoi. hieu van lam duoc va han tai cua tu.
• Adding a wildcard symbol may retrieve word variants: doc sach ky ((((nang ma) or (dang xay))) or (nang x)) hoi. hieu van lam duoc va han tai cua tu*.