Some of my favorite single blade patterns are the Hungarian "kerek fejes bicska" ("round headed pocket knife" referring to the rounded front bolsters), a clasp knife somewhat similar to the copperhead, but closer in size to the folding hunter (5"). It is also called "fejes görbe bicska", a "curved pocketknife with a head".
One of the best makers of this pattern was Imre Polyak. The only web source I have found for his work is:
http://www.accentknives.com/vlad.html
I can assure you that reference to Dracula ("Vlad") and the story about the Transylvanian wild country has nothing to do with the pattern's Hungarian name or traditional use. I am not even sure it was typical for the Transylvanian region, which had a mixed Hungarian, Rumanian, German (Saxon) and other population.
I was told by some makers and sellers in Hungary that the pattern is likely to be quite recent (end of 19th, beginning of 20th Century?), and was allegedly preferred by coachmen. On website of a contemporary Hungarian knifemaker I have read that this pattern goes back to the early 1700s. In Hungary these types of pocketknives were used primarily as eating utensils (for cutting bread, bacon, salami, vegetables) and to a much lesser extent for whittling or other chores.
I still have one with stag handle somewhere. It cost me about the quarter of my monthly salary then, but I had to have it (talk about being a knife nut

).
I have read that in the late 19th and early 20th Century the preferred handle material for these knives was mother of pearl and bone, but I guess wood and horn was used too. While I lived in Hungary I have never seen a modern rendition in other handle material than the native red deer stag or walnut wood.
It is really comfortable to use, but is on the heavy side. I have seen that pattern made in several smaller sizes too, especially for tourists.
By the way this is the only Hungarian pocket knife pattern pictured (and mentioned) in Bernard Levine's book. The particular example there is a recent (communist era) make and an especially crude one, might have been made by an amateur "maker".
Another one I had and liked is somewhat similar to the one the site called "The Classic":
http://www.accentknives.com/classic.html
It had in fact no bolsters, just a stag handle with liners. You might call it a sodbuster, but it is more robust (and much heavier) than the sodbuster.
The ones which resemble the melon tester and are given the fantasy name "The Surgeon" on that site are in fact called "rac bicska" (Serbian pattern pocket knife") or "szalonnazo bicska" ("bacon slicer") and was the preferred pattern to slice the bacon for one's meals.
http://www.accentknives.com/surgeon.html
You might have guessed already that in the past in Hungary (and elsewhere in Europe) bacon was a staple food of farmers, sharecroppers and workers. They did not prepare sandwiches but would cut thin slices off a bacon slab and cubes of the bread and the vegetables they were eating (onions, peppers, tomatoes etc.). The pointy tip is handy to use as a "one-prong" fork too!
Before one wonders, I don't have the slightes intention to promote that site (I find their prices ridiculously inflated). I simply tried to find an illustration for the "ethnic" single blades I grew up with and still remember with some nostalgia.
The Hungarian word for pocketknife, folding knife is "bicska" (pronounced as 'bitch-kah) and comes from the Turkish word "bicak" (bitch-'ahk) which means means 'fixed blade knife'.
But I guess this change in meanings is just logical when you know that the Hungarian word for sword: "kard" comes from the Persian "kard" which means 'fixed blade knife".
After submitting the first version of this post I have searched the net to find more info on master Polyak. It turns out he passed away in February this year at the age of 75.
His knives were sought after in Europe (mainly Germany), and one of his knives was given as a gift to President Bush, the Senior when he visited Hungary.
His craft is continued by his son, Imre Polyak Jr.