Open system for the development of software manuals. - Hristo Tujarov; Ivelin Mihailov (CompSysTech, 2003)

Presentation of a web site using the systematic approach. - Hristo Tujarov; Milena Stefanova; Hristina Moneva (CompSysTech, 2003)

PER model: semantic data models developing. - Hristo Tujarov; Ivelin Mihailov (CompSysTech, 2004)

Educational process model. - Hristo Tujarov; Svetlana Avramova; Stefan Kalchev; Milena Stefanova (CompSysTech, 2008)

Data PER model. - Hristo Tujarov; Stefan Kalchev; Vassil Milev (CompSysTech, 2013)