"Royal Greenwich Observatory." . . . . . . . . "The Greenwich guide to measuring time"@en . "The Greenwich guide to measuring time" . . "Offers an introduction to the concept of time, covering timekeeping tools including calendars, clocks, and watches." . "Measuring time" . . . . . . "What is time? - Patterns in time - Hours and minutes - Calendars - Names of the months - Day names - Timers - First clocks - Today's clocks and watches - Astronomers and timekeeping - What's the time? - Atomic clocks."@en . . . . . . "Juvenile works"@en . "Juvenile works" . . "Clocks and watches Juvenile literature." . . "Time measurements Juvenile literature." . .