[1] He wrote more than 150 novels and more than 3,000 lyrics for popular music, which made him the most prolific writer in the history of Slovenian literature.

In the same time he also collected descriptions of folk customs and traditions for the ethnologist Niko Kuret of the Institute of Slovenian Ethnology, and had a regular column about it in Gorenjski glas.

In 1973, he enrolled in Slovenian studies at the Faculty of Arts of the Ljubljana University and graduated in 1978 (thesis title: Stilno označena sredstva v Pohlinovem jeziku na leksikalni in sintaktični ravni [Stylistically marked means in Pohlin's language at the lexical and syntactic level].

[4] He mostly worked in the afternoon, at night and on weekends, while in the morning hours he attended lectures and performed regular study duties.

He followed the routes taken by Jack London to Alaska, of Jules Verne through France and to the top of Mont Blanc, in the footsteps of the Slovenian-Croatian ethnologist Ivan Benigar (1883–1950) through Argentina, along the routes of the anthropologist William W. Howells (1908–2005) through Namibia, of the priest and mountaineer Janko Mlakar across European mountains, including Jungfrau, following the paths of the Aboriginal Australians, of the Maori people in New Zealand and the voyages of the poet France Prešeren in Slovenia, Austria and Moravia.

[10] According to literary historian Miran Hladnik, known for analysis of Slovenian rural stories ... with this book Sivec gave the reader, who had previously only been offered a socially critical or existentialist variant of farm life, a real, romantic, popular peasant story, about which the literary critics and historians will hardly write anything good, but the reader nevertheless enjoys it again and again.

[6] Among his most popular books are historical novels (for clarity only English translations of the original titles are given): the Carantania trilogy (King Samo, Emperor Arnulf, Viscountess Emma); a tetralogy about the Romans in Slovenia (The Last Celtic Chieftain, The Fatal Emonian Beauty, The Tempest over the Cold River, Attila, Scourge of God); pentalogy about the Counts of Celje (Knights of the Morning Dawn, The Shining Stars of Celje, The Queen with Three Crowns, The Lonely Wild Flower, The Last Viscount of Celje); the first European Iron Age novel – Showdown at the Full Moon; a collection of Slovenian Castle Stories (Don't Forget Our Love, Lost Heart, Blind Countess, Blue Rose, Lord of Visoko, Love at Kolpa river); biographical novels (about Prešeren, Gregorčič, Jurčič, Tavčar, Trdina, Aljaž, Murn, Plečnik and others); the collection Dotik srca [Touch of Heart] (I Come to the Shore Every Day, When You Touch the Sky, At Sunset, Seven Broken Roses, Blooming Slovenia, Beauty of the Trnovo parish).

[2] Branko Gradišnik encouraged Sivec to start writing for the youth and the first such work was the adventure novel Pozabljeni zaklad (Forgotten Treasure, 386 pages, 1978, reprinted 2001).

[12] In Sivec biography on the site of the Slovenian Writer's Association his work was classified in 13 groups: Several of his books have been translated into German, English (The X Factor / Confessions of a naive fashion model[13]), French and Italian.

Sivec presents his books at school Reading badge[17] events and literary evenings, and also acts as a keynote speaker.