- ASTRONOMY FOR YOUNG AUSTRALIANS.免费
- DAILY MOTION OF THE EARTH.免费
- ROTUNDITY OF THE EARTH.免费
- SIZE OF THE WORLD免费
- THE EARTH NOT QUITE ROUND.免费
- ANNUAL MOTION.免费
- THE SEASONS.免费
- PRECESSION OF THE EQUINOXES.免费
- FIXED STARS NOT FIXED.免费
- DISTANCES AND SIZES OF THE STARS.免费
- CONSTELLATIONS.免费
- DOUBLE STARS.免费
- PERIODICAL AND VARIABLE STARS.免费
- MILKY WAY.免费
- THE NEBUL?免费
- THE SUN AND PLANETS.免费