Genre
- Maps 59 canlyniadau
- Congresses 24 canlyniadau
- Observations 21 canlyniadau
- Periodicals 8 canlyniadau
- Surveys 6 canlyniadau
- Guidebooks 4 canlyniadau
- Bibliography 3 canlyniadau
- aps 3 canlyniadau
- Bathymetric maps 2 canlyniadau
- Handbooks, manuals, etc 2 canlyniadau
- Statistics 2 canlyniadau
- Aerial photographs 1 canlyniadau
- Catalogs and collections 1 canlyniadau
- Databases 1 canlyniadau
- Indexes 1 canlyniadau
- Pictorial works 1 canlyniadau
- Remote-sensing images 1 canlyniadau
- Sources 1 canlyniadau
- Tables 1 canlyniadau