Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cam thuc » am thuc, cam thu, can thuc
nam thuc » nam thuoc, am thuc, nam thu
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang
sach ty » sach y, sach tu, sach thu
danh di » danh du, xanh di, danh dien
hanh de » hanh ve, hanh kem
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 ty nang xa hoi. hieu qua ((cam thuc) OR (nam thuc)) va ((danh di) or (hanh de)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty nang xa hoi. hieu qua ((cam thuc) OR (nam thuc)) va ((danh di) OR (hanh de)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty nang xa hoi. hieu qua ((cam thuc) OR (nam thuc)) va ((danh di) or (hanh de)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ty nang xa hoi. hieu qua ((cam thuc) OR (nam thuc)) va ((danh di) or (hanh de)) cua tre*.