Perhaps you should try some spelling variations:
nang may » mang may, bang may, nang cao
hoc viet » hoc hien
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
ve cam » ve cham, ve cac, va cam
vi hoc » li hoc, va hoc

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 may) OR (nang ma)) hoi. hieu ve cam xuc ((tuan anh) or (van minh)) vi hoc viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang may) OR (nang ma)) hoi. hieu ve cam xuc ((tuan anh) OR (van minh)) vi hoc viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang may) OR (nang ma)) hoi. hieu ve cam xuc ((tuan anh) or (van minh)) vi hoc viet".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang may) OR (nang ma)) hoi. hieu ve cam xuc ((tuan anh) or (van minh)) vi hoc viet*.