Yes, if you append the parameter ?source= followed by the name of the source to a booking link - for example, bookeo.com/yogalifestyle?source=my_custom_campaign or to a gift voucher link, you can track where the sale was originated from in Bookeo.
The same parameter can be used if you use the booking widget, ex:
Of course you can use any word instead of "my_custom_campaign", as long as it's made of numbers, letters, _ or - , and is up to 64 characters long.
When customers make a booking by clicking on the link (or from a page where the custom widget code is used) the source will show:
1. in the HOW section, Source  field of your bookings
2. In the Source column in your booking report - that you can generate in Marketing>Reports>Bookings.