In viticulture, consultants are active in various fields such as soil science, vineyard care, cellar technology and vinification as well as sales and marketing. Such specialists are particularly sought after when wineries and cellars are founded or reorganised. Many supermarket chains, restaurants and airlines also seek advice from them. The top people are mostly trained oenologists and/or ampelographers. Among the most famous and first is the already legendary Russian-born André Tchelistcheff (1901-1994), who worked first in Napa Valley, California, and later in Europe. The German agricultural engineer and author of many wine reference books Dr. Hans Ambrosi (1925-2012) spent 11 years in South Africa working for various wineries.