If you are ever concerned about people copying your web based content, then you can use proprietary services like Copyscape to protect your work.
However, there is, of course, a cost associated with that so if you’re only running perfunctory checks now and again to see where (or if) your material has been repeated, you can simply use trusty old Google.
Simply highlight a sample of several words within your text that should be unique to your own content and hit CTRL ‘C’ i.e. control C. This then copies that text to your clipboard.
Go to google and enter two separate double quotes as in “”. Then, paste your clipboard between the pair of double quotes with the CTRL ‘V’ (control V) and hit “search”.
Because entering text within a pair of double quotes asks Google to look for that text exactly , the results returned (if any) must include the text you searched for. With any luck, the return will show “0 Results” and you’ll have no cause for concern.
If (apart from occasional citations of your work) you have someone that is repeatedly and grossly plagiarising your work, you may wish to consider issuing a semi-formal ‘cease and desist’ request before taking more drastic action.