Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
nang tai » hang tai, tang tai, sang tai
ve cham » va cham, ve chat, ve chim
kem cua » em cua, keo cua, diem cua
vu cham » va cham, vu kham, tu cham
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky ((nang ma) or (nang tai)) hoi. hieu ((ve cham) or (vu cham)) cuu van hanh kem cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((nang ma) OR (nang tai)) hoi. hieu ((ve cham) OR (vu cham)) cuu van hanh kem cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((nang ma) or (nang tai)) hoi. hieu ((ve cham) or (vu cham)) cuu van hanh kem cua tre*.