Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
hanh doi » thanh doi, hanh noi, hang doi
van hanh » van thanh, ban hanh, van anh
vien cac » vien bach, vien dai, vien da
vien cam » vien cao, vien nam, vien can
doc sach » hoc sach, nuoc sach, dac sac
nang xa » nang x, lang xa, nang ma
ly nang » ky nang, ly hang, ly vang
duc van » duc va, duc tan, duc manh
doi cua » dai cua, hoi cua
cua tu » cua tuc, cua su, cua cu

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) or (doc sach)) ly nang xa hoi. hieu ((vien cam) OR (vien cac)) duc van hanh doi cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ly nang xa hoi. hieu ((vien cam) OR (vien cac)) duc van hanh doi cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (doc sach)) ly nang xa hoi. hieu ((vien cam) OR (vien cac)) duc van hanh doi cua tu".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) ly nang xa hoi. hieu ((vien cam) OR (vien cac)) duc van hanh doi cua tu*.