Perhaps you should try some spelling variations:
va thanh » ban thanh, va tinh, le thanh
vu sach » vu bach, su sach, vu khach
cam tuc » cam xuc, cam tu, nam thuc
lay cua » ly cua, day cua, lai cua
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
nang co » nang cao, nang doc, nang noi
nang o » nang ho, nang ro, nang x
ve cam » ve cham, ve cac, va cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky ((nang o) or (nang co)) hoi. hieu ve cam tuc ((va thanh) OR (gia thanh)) lay cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky ((nang o) OR (nang co)) hoi. hieu ve cam tuc ((va thanh) OR (gia thanh)) lay cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky ((nang o) or (nang co)) hoi. hieu ve cam tuc ((va thanh) OR (gia thanh)) lay cua tre".
• Adding a wildcard symbol may retrieve word variants: vu sach ky ((nang o) or (nang co)) hoi. hieu ve cam tuc ((va thanh) OR (gia thanh)) lay cua tre*.