How to Concatenate the content of  two different URL and display in one window?

example : lets say i have course and under course i have two unit (all in links form)

    course link

              --Unit1 Link

              --Unit 2 Link

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               1st unit contains URL1

               2nd unitcontains URL2

upon clicking the course links ,i should display the content of two units combinedin single window( like book format).

Thanks in advance for the help

Vinay