Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
luc van » luoc van, luu van, duc van
sach ty » sach y, sach thu, xach tay
nang ma » tang ma, sang ma, nang cao
sach tu » sach thu, cach tu, sach uu
cuu tre » cua tre, cau tren, cau treo
ma hoi » mai hoi, xa hoi, ma hoa
ve cau » ke cau, va cau, le cau
ve cac » va cac, vien cac
vi cuu » vi luu, vinh cuu

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc ((sach ty) OR (sach tu)) nang ma hoi. hieu ((ve cau) or (ve cac)) luc van hanh vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc ((sach ty) OR (sach tu)) nang ma hoi. hieu ((ve cau) OR (ve cac)) luc van hanh vi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc ((sach ty) OR (sach tu)) nang ma hoi. hieu ((ve cau) or (ve cac)) luc van hanh vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: thuoc ((sach ty) OR (sach tu)) nang ma hoi. hieu ((ve cau) or (ve cac)) luc van hanh vi cuu tre*.