Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
su sach » so sach, vu sach
cam dan » cac dan, ca dan, nam dan
sach ky » sac ky, sach y, sach ty
cac xuc » cam xuc, chat xuc, cac cuoc
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
dan vi » doan vi, don vi, dan va
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky ((nang x) or (nang ma)) hoi. hieu van ((cac xuc) OR (cac nuoc)) cam dan vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang x) OR (nang ma)) hoi. hieu van ((cac xuc) OR (cac nuoc)) cam dan vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang x) or (nang ma)) hoi. hieu van ((cac xuc) OR (cac nuoc)) cam dan vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang x) or (nang ma)) hoi. hieu van ((cac xuc) OR (cac nuoc)) cam dan vi cua tre*.