Do there exist Lorentzian manifolds all of whose light-like geodesics are periodic? A surprising fact is that such manifolds exist in abundance in (2 + 1)-dimensions (though in higher dimensions…

This is an EXACT reproduction of a book published before 1923. This IS NOT an OCR’d book with strange characters, introduced typographical errors, and jumbled words. This book may have…

La lune / par Amedee GuilleminDate de l'edition originale: 1866Sujet de l'ouvrage: Lune – VulgarisationCollection: Petite encyclopedie populaireCe livre est la reproduction fidele d'une oeuvre publiee avant 1920 et fait…

This is a reproduction of a book published before 1923. This book may have occasional imperfections such as missing or blurred pages, poor pictures, errant marks, etc. that were either…

This is a reproduction of a book published before 1923. This book may have occasional imperfections such as missing or blurred pages, poor pictures, errant marks, etc. that were either…

Les Mondes Causeries Astronomiques est un livre ?????crit par Amedee Guillemin et publi????? en 1863. Il s'agit d'un ouvrage qui traite de l'astronomie et qui est destin????? ?????? un public…

This is an EXACT reproduction of a book published before 1923. This IS NOT an OCR’d book with strange characters, introduced typographical errors, and jumbled words. This book may have…

Meet Allie. She lives with her mom, her dad, and one awfully super cat named Mr. Pib. Allie and Mr. Pib are always having adventures, even when they are at…