Perhaps you should try some spelling variations:
tan thanh » tran thanh, tang thanh, toan thanh
toc sach » hoc sach, doc sach, thuoc sach
vinh cua » sinh cua, tinh cua, dinh cua
hieu van » hieu va, thien van, lieu va
tan hanh » tang hanh, toan hanh, tran hanh
bac dan » bach dan, cac dan, ban dan
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
bac dac » bac dai, ban dac, cac dac
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh

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 dang xa hoi. hieu van ((bac dac) or (bac dan)) ((tan hanh) or (tan thanh)) vinh cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky dang xa hoi. hieu van ((bac dac) OR (bac dan)) ((tan hanh) OR (tan thanh)) vinh cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach ky dang xa hoi. hieu van ((bac dac) or (bac dan)) ((tan hanh) or (tan thanh)) vinh cua tre*.