A certain number of letters had been considered as unpublishable.

一部分信件被认为是不能出版的。

There is a final volume, Selected Letters, brought out by the priceless Richard Ellmann in which he publishes a certain number of them which had been considered as unpublishable in the first tomes.

他在这个信件选集里，出版了一些曾经在前面几大册，被认为是不可出版的信件。