If a review of the frequency distributions for each source points to a many-to-one condition and one source has only unique values, then it is a likely reference source.
如果查看每个源的频率分布发现存在多对一的情况，并且一个源只有一个惟一的值，那么它很可能就是引用源。
2
That is, each probe into the second table reference and the third table reference would efficiently locate the only record that matches the join condition.
也就是说，进入第二个表引用和第三个表引用的探测只将有效地定位匹配联接条件的记录。
3
Putnam claims that one condition which is crucial for successful reference is that there be an appropriate causal connection between the object referred to and the speaker referring.