1
Cyhoeddwyd: [1942]
Superior document: Title is part of eBook package: De Gruyter CUP eBook Package Archive 1898-1999 (pre Pub)
2
Cyhoeddwyd: [2011]
Superior document: Title is part of eBook package: De Gruyter DGBA Library Information Science <1990
Links: Cael y testun llawn; Cael y testun llawn; Cover