Discoveries in science : how they are made
- New York : Fawcett Publications, 1968.
- 124 páginas : 2 h.; 18 cm.
- Ladder : 2000 words ; L-52 .
This Ladder Edition has been especially prepared for the beginning reader.This edition is for readers for whom English is a second language. It can be anyone whos has learned 2,000 words of english.