| 其他書名 | Two Lectures Delivered on Invitation of the Committee for Academic Interests of the University of South Africa, on August 20 and 21, 1957 |
| 出版 | University of South Africa, 1957 |
| URL | http://books.google.com.hk/books?id=VevSAAAAMAAJ&hl=&source=gbs_api |