▁costs , ▁then ▁the ▁H ME s ▁disappear . ▁Head ▁et ▁al . ▁( 2 0 0 2 ) ▁cons iders ▁four ▁kinds ▁of ▁horizontal ▁product ▁different iation ▁models ▁to ▁examine ▁the ▁per vas iveness ▁of ▁the ▁H ME s . ▁Re verse ▁H ME s ▁are ▁found ▁based ▁on ▁the ▁Mark us en - V en ables ▁( 1 9 8 8 ) ▁model ▁that ▁vari eties ▁are ▁linking ▁to ▁nations ▁rather ▁than ▁fir ms . ▁Be hr ens ▁( 2 0 0 5 ) ▁discuss es ▁the ▁H ME s ▁in ▁the ▁context ▁of ▁regional ▁econom ics . ▁When ▁non - tr aded ▁goods ▁are ▁taken ▁into ▁consideration , ▁the ▁H ME s ▁may ▁be ▁offset , ▁whereas ▁a ▁reverse ▁H ME ▁may ▁arise . ▁Yu ▁( 2 0 0 5 ) ▁shows ▁that ▁if ▁consumer ▁preference ▁follows ▁the ▁form ▁of ▁a ▁constant ▁demand ▁el astic ity ▁of ▁substitution ▁between ▁the ▁hom ogeneous ▁and ▁the ▁composite ▁of ▁differenti ated ▁goods , ▁then ▁the ▁reverse ▁H ME s ▁may ▁occur ▁depending ▁on ▁the ▁level ▁of ▁el astic ity . ▁ ▁References ▁ ▁Category : Intern ational ▁trade ▁theory <0x0A> </s> ▁For ▁the ▁mart yr , ▁see ▁The of rid . ▁Th io fr id ▁( d ied ▁ 1 1 1 0 ) ▁was ▁the ▁Bened ict ine ▁ab bot ▁of ▁E ch tern ach ▁Ab bey , ▁and ▁writer ▁of ▁works ▁in ▁several ▁different ▁areas . ▁He ▁is ▁one ▁of ▁the ▁few ▁medieval ▁writers ▁to ▁discuss ▁the ▁cult ▁of ▁re lic