Text ( visual ) : unmediated General relativity : the essentials / Carlo Rovelli. -- : pbk.. -- Cambridge : Cambridge University Press , 2021. -- x, 163 p. : ill. ; 23 cm. -- Includes bibliographical references and index. -- ISBN 9781009013697 ; (BC11116027) ; https://ci.nii.ac.jp/ncid/BC11116027 Author Heading(s): Rovelli, Carlo. -- Classification(s): DC23 : 530.11 ; LCC : QC173.6. -- Subject Heading(s): LCSH : Relativity (Physics) ; LCSH : General relativity (Physics) ; FREE : SCIENCE / Space Science / Cosmology bisacsh